Infrared athermalization optical lens

Abstract

The invention discloses an infrared athermalization optical lens. The infrared athermalization optical lens sequentially comprises a first lens with positive focal power, a second lens with negative focal power and a third lens with positive focal power from an object side to an image side along an optical axis, wherein the object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the object side surface of the second lens is a convex surface or a concave surface, and the image side surface is a concave surface; the object side surface and the image side surface of the third lens are convex surfaces; the first lens, the second lens and the third lens are all lenses without diffraction surfaces, the first lens, the second lens and the third lens are all made of chalcogenide glass, and the refractive index of the material of the first lens or the third lens is larger than 3.

Description

Technical Field

[0001] This application relates to the field of optical components, specifically to an infrared calorimetric optical lens. Background Technology

[0002] Compared to cooled detectors, uncooled detectors require no cooling device, offering advantages such as lighter weight, lower cost, and faster start-up, making them widely used in security, temperature measurement, and automotive applications. With the maturation of uncooled detector technology, long-wave infrared uncooled optical systems are finding increasingly widespread use. However, parameters such as the refractive index, curvature, and thickness of lenses in infrared optical systems vary significantly with temperature. Changes in operating temperature can cause defocusing in infrared optical systems, leading to deterioration in image quality. Therefore, pyrolysis techniques are needed to eliminate or reduce the effects of temperature, ensuring good image quality under varying temperature conditions.

[0003] Thermal aberration mitigation techniques for infrared optical systems include passive optical compensation, which utilizes the differences in thermal properties of different materials and optical power matching to achieve temperature compensation. This method is simple in structure and easy to assemble. However, in related technologies, the lens materials used in passive optical compensation are typically single-crystal germanium, zinc selenide, or zinc sulfide, resulting in high material costs. Furthermore, the use of diffraction surface structures within the lens to utilize their negative thermal aberration characteristics complicates the lens manufacturing process. Summary of the Invention

[0004] This application provides an infrared athermalized optical lens, which includes, along the optical axis from the object side to the image side, a first lens with positive optical power, a second lens with negative optical power, and a third lens with positive optical power; wherein, the object side of the first lens is convex and the image side is concave; the object side of the second lens is either convex or concave and the image side is concave; both the object side and the image side of the third lens are convex; the first lens, the second lens, and the third lens are all diffraction-free lenses, and the materials of the first lens, the second lens, and the third lens are all chalcogenide glass, and the refractive index of the material of the first lens or the third lens is greater than 3.

[0005] According to an exemplary embodiment of this application, the total effective focal length f of the infrared athermalized optical lens, the refractive index n1 of the first lens, the aperture value FNO of the infrared athermalized optical lens, and the radius of curvature R1 of the object side surface of the first lens satisfy: 1.37≤f×(n1-1) / (FNO×R1)≤2.01.

[0006] According to an exemplary embodiment of this application, the maximum effective aperture D3 of the third lens, the half-image height H of the infrared athermalized optical lens, and the total effective focal length f of the infrared athermalized optical lens satisfy: 0.2mm. -1≤D3 / (H×f)≤0.3mm -1 .

[0007] According to an exemplary embodiment of this application, the total effective focal length f of the infrared athermalized optical lens and the half-image height H of the infrared athermalized optical lens satisfy the following condition: 2.7 ≤ f / H ≤ 5.1.

[0008] According to an exemplary embodiment of this application, the effective focal length f1 of the first lens and the total effective focal length f of the infrared anechoic optical lens satisfy: 0.61≤f1 / f≤1.38.

[0009] According to an exemplary embodiment of this application, the effective focal length f2 of the second lens and the total effective focal length f of the infrared anechoic optical lens satisfy: 0.39≤|f2 / f|≤0.51.

[0010] According to an exemplary embodiment of this application, the effective focal length f3 of the third lens and the total effective focal length f of the infrared anechoic optical lens satisfy: 0.39≤f3 / f≤0.77.

[0011] According to an exemplary embodiment of this application, the Abbe number v1 of the first lens and the Abbe number v2 of the second lens satisfy: 61.3≤v1-v2≤248.65.

[0012] According to an exemplary embodiment of this application, with a spatial frequency of 42 cycles / mm, the modulation transfer function value of the infrared anechoic optical lens at room temperature in the wavelength range of 8μm-12μm is greater than 90% of the diffraction limit.

[0013] According to an exemplary embodiment of this application, the total effective focal length f of the infrared athermalized optical lens satisfies: 13mm ≤ f ≤ 25mm. Attached Figure Description

[0014] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0015] Figure 1 A schematic diagram of the structure of an infrared athermalized optical lens according to Embodiment 1 of this application is shown;

[0016] Figure 2 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 1 of this application at room temperature is shown;

[0017] Figure 3 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 1 of this application at -40°C is shown.

[0018] Figure 4 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 1 of this application at 80°C is shown.

[0019] Figure 5 A blur pattern of an infrared athermalized optical lens according to Embodiment 1 of this application is shown;

[0020] Figure 6 A schematic diagram of the structure of an infrared athermalized optical lens according to Embodiment 2 of this application is shown;

[0021] Figure 7 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 2 of this application at room temperature is shown;

[0022] Figure 8 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 2 of this application at -40°C is shown.

[0023] Figure 9 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 2 of this application at 80°C is shown.

[0024] Figure 10 A blur pattern of an infrared athermalized optical lens according to Embodiment 2 of this application is shown;

[0025] Figure 11 A schematic diagram of the structure of an infrared athermalized optical lens according to Embodiment 3 of this application is shown;

[0026] Figure 12 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 3 of this application at room temperature is shown;

[0027] Figure 13 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 3 of this application at -40°C is shown.

[0028] Figure 14 The modulation transfer function of the infrared athermalized optical lens according to Embodiment 3 of this application at 80°C is shown.

[0029] Figure 15 A diffusion pattern of an infrared athermalized optical lens according to Embodiment 3 of this application is shown. Detailed Implementation

[0030] To better understand this application, various aspects of this application are described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way.

[0031] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0032] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the image plane is called the image-side surface of the lens.

[0033] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprises" as used in this specification indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. It should be noted that in this specification, the expressions "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features.

[0034] Unless otherwise specified, all terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Terms shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly stated herein.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] This application provides an infrared athermalized optical lens, comprising a first lens, a second lens, and a third lens sequentially along the optical axis from the object side to the image side. The first lens has positive optical power, with a convex object side and a concave image side; the second lens has negative optical power, with either a convex or concave object side and a concave image side; the third lens has positive optical power, with both its object side and image side being convex. All three lenses are diffraction-free lenses, and all are made of chalcogenide glass. The refractive index of the material of the first or third lens is greater than 3. The use of a high-refractive-index material for the first or third lens shortens the overall optical length of the infrared athermalized optical lens, making its structure more compact.

[0037] In this application, a diffraction-free lens refers to a lens that does not contain a diffraction surface structure. The image-side and object-side surfaces of the lens can be spherical, aspherical, or freeform surfaces, etc. In an exemplary embodiment, the object-side surfaces of the first lens, the second lens, and the third lens can each be independently spherical or aspherical, and the image-side surfaces of the first lens, the second lens, and the third lens can each be independently spherical or aspherical. Aspherical surfaces have continuously varying curvature, thus having the advantage of improving distortion aberrations and astigmatism aberrations, and can eliminate aberrations that occur during imaging as much as possible, thereby improving the imaging quality of infrared athermalized optical lenses.

[0038] In an exemplary embodiment, the total effective focal length f of the infrared athermalized optical lens, the refractive index n1 of the first lens, the aperture value FNO of the infrared athermalized optical lens, and the radius of curvature R1 of the object-side surface of the first lens satisfy: 1.37 ≤ f × ​​(n1 - 1) / (FNO × R1) ≤ 2.01. By rationally configuring the total effective focal length f of the infrared athermalized optical lens, the refractive index n1 of the first lens, the aperture value fNO of the infrared athermalized optical lens, and the radius of curvature R1 of the object-side surface of the first lens, the degree of curvature of the first lens can be controlled, thereby reducing the manufacturing difficulty of the first lens.

[0039] In an exemplary embodiment, the maximum effective aperture D3 of the third lens, the half-image height H of the infrared athermalized optical lens, and the total effective focal length f of the infrared athermalized optical lens satisfy: 0.2mm. -1 ≤D3 / (H×f)≤0.3mm -1 By rationally configuring the effective aperture of the image side of the third lens, the half-image height of the infrared athermalized optical lens, and the total effective focal length of the infrared athermalized optical lens, it is beneficial to control the effective aperture of the third lens, thereby helping to control the aperture of the tail film, increasing the adaptability of the infrared athermalized optical lens, and reducing the material cost of the infrared athermalized optical lens.

[0040] In an exemplary embodiment, the total effective focal length f of the infrared athermalized optical lens and the half-image height H of the infrared athermalized optical lens satisfy the condition: 2.7 ≤ f / H ≤ 5.1. By controlling the range of the ratio between the total effective focal length and the half-image height of the infrared athermalized optical lens, it is beneficial to improve the resolving power.

[0041] In an exemplary embodiment, the effective focal length f1 of the first lens and the total effective focal length f of the infrared athermalized optical lens satisfy the condition: 0.61 ≤ f1 / f ≤ 1.38. Furthermore, the infrared athermalized optical lens may also include an aperture stop, which can be disposed on the object-side surface of the first lens to effectively reduce the amount of light entering the infrared athermalized optical lens and shorten the total optical length of the infrared athermalized optical lens. By controlling the range of the ratio between the effective focal length of the first lens and the total effective focal length of the infrared athermalized optical lens, it helps to correct the spherical aberration and coma of the infrared athermalized optical lens. It should be noted that the position of the aperture stop disclosed herein is merely an example and not a limitation; in alternative embodiments, the aperture stop can be placed in other positions as needed.

[0042] In an exemplary embodiment, the effective focal length f2 of the second lens and the total effective focal length f of the infrared athermalized optical lens satisfy the condition: 0.39 ≤ |f2 / f| ≤ 0.51. By controlling the range of the ratio between the effective focal length of the second lens and the total effective focal length of the infrared athermalized optical lens, the effective focal length of the second lens can be controlled, which helps to coordinate with the first and third lenses, thereby balancing the chromatic aberration of the infrared athermalized optical lens.

[0043] In an exemplary embodiment, the effective focal length f3 of the third lens and the total effective focal length f of the infrared athermalized optical lens satisfy the condition: 0.39 ≤ f3 / f ≤ 0.77. By controlling the range of the ratio between the effective focal length of the third lens and the total effective focal length of the infrared athermalized optical lens, the effective focal length of the third lens can be controlled, which helps to improve the imaging quality of the infrared athermalized optical lens and reduce its sensitivity.

[0044] In an exemplary embodiment, the Abbe number v1 of the first lens and the Abbe number v2 of the second lens satisfy: 61.3 ≤ v1 - v2 ≤ 248.65. By rationally configuring the Abbe numbers of the first and second lenses, it is helpful to reduce higher-order aberrations in infrared athermalized optical lenses.

[0045] In an exemplary embodiment, with a spatial frequency of 42 cycles / mm, the modulation transfer function value of the infrared athermal optical lens at room temperature in the wavelength range of 8μm-12μm is greater than 90% of the diffraction limit, thus achieving high-definition imaging.

[0046] In an exemplary embodiment, the total effective focal length f of the infrared athermalized optical lens satisfies: 13mm≤f≤25mm, which makes the applicable focal length range of the infrared athermalized optical lens wide.

[0047] In an exemplary embodiment, the infrared athermalized optical lens may further include a protective glass located on the side of the third lens opposite to the second lens, that is, the protective glass is located between the third lens and the image plane, and the light from the object passes sequentially through the first lens to the third lens and the protective glass and is finally imaged on the image plane.

[0048] The infrared athermalized optical lens provided in this application uses chalcogenide glass as the material for the first, second, and third lenses. Through reasonable material matching and optical power distribution, it can achieve the function of eliminating thermal differences under the condition that none of the three lenses have diffraction surfaces. As a result, it has good imaging quality in a wide temperature range of -40℃ to 80℃. The absence of diffraction surfaces in the lenses also reduces the manufacturing difficulty of the lenses. The use of chalcogenide glass as the material for the lenses can also reduce the cost of the infrared athermalized optical lens.

[0049] Those skilled in the art will understand that the number of lenses constituting the infrared athermalized optical lens can be varied to obtain the various results and advantages described herein without departing from the technical solutions claimed in this application. For example, although a three-lens configuration has been described in the embodiment, the infrared athermalized optical lens is not limited to including three lenses. If desired, the infrared athermalized optical lens may also include other numbers of lenses.

[0050] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of an infrared athermalized optical lens applicable to the above-described embodiments.

[0051] Example 1

[0052] The following is for reference Figure 1 The infrared athermal optical lens according to Embodiment 1 of this application is described.

[0053] like Figure 1 As shown, the infrared athermalized optical lens, along the optical axis from the object side to the image side, includes a first lens L1, a second lens L2, a third lens L3, and a protective glass CG. The first lens L1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens L2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The protective glass CG includes an object-side surface S7 and an image-side surface S8. Light from the object passes sequentially through surfaces S1 to S8 and is ultimately imaged onto the image surface IMA. The infrared athermalized optical lens also includes an aperture stop (STOP) located on the object-side surface of the first lens L1.

[0054] Table 1 shows the basic parameters of each lens in the infrared athermalized optical lens of this embodiment. The units for radius of curvature, thickness / distance, effective focal length, and effective aperture are all millimeters (mm).

[0055] Table 1

[0056]

[0057]

[0058] In this embodiment, both the first lens L1 and the second lens L2 are aspherical lenses. The surface shape x of the aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0059]

[0060] Where x is the distance vector from the vertex of the aspherical surface at a height h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the conic coefficient k and the higher-order coefficients A4, A6, A8, A4, A5, A6, A7, A8, A9, A1 ... 10 .

[0061] Table 2

[0062] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S1 0 3.64E-06 -1.25E-07 1.93E-09 -2.33E-11 S2 0 -7.18E-06 6.63E-08 -7.49E-10 0.00E+00 S3 0 -2.18E-05 7.38E-07 -9.91E-09 5.14E-11 S4 0 -2.04E-05 7.07E-07 -3.90E-09 -2.82E-10

[0063] In this embodiment, the first lens L1, the second lens L2, and the third lens L3 are all made of chalcogenide glass and do not contain diffraction surface structures. The total effective focal length f of the infrared anechoic optical lens in this embodiment is 13.5 mm, the aperture value FNO is 1, the half-image height H is 4.92 mm, and the total optical length is 21.55 mm.

[0064] Figure 2 This is the modulation transfer function (MTF) diagram of the infrared athermalized optical lens provided in this embodiment at room temperature (25°C). Figure 3 This is a modulation transfer function graph of the infrared athermalized optical lens provided in this embodiment at -40°C. Figure 4 This is a modulation transfer function diagram of the infrared athermalized optical lens provided in this embodiment at 80°C. Figure 5 This is a blur pattern of the infrared athermalized optical lens provided in this embodiment. Figures 2-5 It is known that the infrared athermalized optical lens has good imaging quality in the temperature range of -40℃ to 80℃. At a spatial frequency of 42 cycles / mm, the modulation transfer function value of the central field of view of the infrared athermalized optical lens at room temperature in the wavelength range of 8μm-12μm is greater than 90% of the diffraction limit.

[0065] Example 2

[0066] The following is for reference Figure 6The infrared athermal optical lens according to Embodiment 2 of this application is described.

[0067] like Figure 6 As shown, the infrared athermalized optical lens, along the optical axis from the object side to the image side, includes a first lens L1, a second lens L2, a third lens L3, and a protective glass CG. The first lens L1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens L2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The protective glass CG includes an object-side surface S7 and an image-side surface S8. Light from the object passes sequentially through surfaces S1 to S8 and is ultimately imaged onto the image surface IMA. The infrared athermalized optical lens also includes an aperture stop (STOP) located on the object-side surface of the first lens L1.

[0068] Table 3 shows the basic parameters of each lens in the infrared athermalized optical lens of this embodiment. The units for radius of curvature, thickness / distance, effective focal length, and effective aperture are all millimeters (mm).

[0069] Table 3

[0070]

[0071]

[0072] In this embodiment, both the first lens L1 and the second lens L2 are aspherical lenses. Table 4 shows the conic coefficient k and the higher-order coefficients A4, A6, A8, and A4 of each aspherical lens S2-S4 in this embodiment. 10 .

[0073] Table 4

[0074] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S2 0 -3.12E-06 4.37E-08 -3.52E-10 1.27E-12 S3 0 -1.23E-05 2.55E-07 -2.76E-09 1.28E-11 S4 0 -1.64E-05 4.47E-07 -6.90E-09 4.43E-11

[0075] In this embodiment, the first lens L1, the second lens L2, and the third lens L3 are all made of chalcogenide glass and do not contain diffraction surface structures. The total effective focal length f of the infrared anechoic optical lens in this embodiment is 18mm, the aperture value FNO is 1, the half-image height H is 4.92mm, and the total optical length is 26.95mm.

[0076] Figure 7 The modulation transfer function diagram of the infrared athermalized optical lens provided in this embodiment at room temperature (25°C) is shown. Figure 8 This is a modulation transfer function graph of the infrared athermalized optical lens provided in this embodiment at -40°C. Figure 9 This is a modulation transfer function diagram of the infrared athermalized optical lens provided in this embodiment at 80°C. Figure 10This is a blur pattern of an infrared athermalized optical lens provided in this embodiment. Figures 7-10 It is known that the infrared athermalized optical lens has good imaging quality in the temperature range of -40℃ to 80℃. At a spatial frequency of 42 cycles / mm, the modulation transfer function value of the infrared athermalized optical lens in the central field of view at room temperature in the wavelength range of 8μm-12μm is greater than 90% of the diffraction limit.

[0077] Example 3

[0078] The following is for reference Figure 11 The infrared athermal optical lens according to Embodiment 3 of this application is described.

[0079] like Figure 11 As shown, the infrared athermalized optical lens, along its optical axis from the object side to the image side, comprises a first lens L1, a second lens L2, a third lens L3, and a protective glass CG. The first lens L1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens L2 has negative optical power, with its object-side surface S3 being concave and its image-side surface S4 being concave. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The protective glass CG includes an object-side surface S7 and an image-side surface S8. Light from the object passes sequentially through surfaces S1 to S8 and is ultimately imaged onto the image surface IMA. The infrared athermalized optical lens also includes an aperture stop (STOP) located on the object-side surface of the first lens L1.

[0080] Table 5 shows the basic parameters of each lens in the infrared athermalized optical lens of this embodiment. The units for radius of curvature, thickness / distance, effective focal length, and effective aperture are all millimeters (mm).

[0081] Table 5

[0082]

[0083]

[0084] In this embodiment, the first lens L1, the second lens L2, and the third lens L3 are all aspherical lenses. Table 6 shows the conic coefficient k and the higher-order coefficients A4, A6, A8, and A6 for each aspherical surface S1, S2, S4-S6 in this embodiment. 10 A 12 A 14 .

[0085] Table 6

[0086] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> S1 0 -7.11E-06 4.73E-08 -1.06E-09 3.63E-12 -1.08E-14 S2 0 5.73E-06 6.59E-08 -1.81E-09 5.02E-12 -3.64E-15 S4 0 -1.76E-04 6.43E-07 -5.71E-10 -1.35E-11 7.21E-14 -1.42E-16 S5 0 -5.40E-05 -2.62E-08 1.23E-09 -3.48E-12 4.22E-15 S6 0 2.16E-05 -1.68E-07 8.11E-10 0.00E+00 0.00E+00

[0087] In this embodiment, the first lens L1, the second lens L2, and the third lens L3 are all made of chalcogenide glass and do not contain diffraction surfaces. The total effective focal length f of the infrared athermalized optical lens in this embodiment is 25mm, the aperture value FNO is 1, the half-image height H is 4.92mm, and the total optical length is 41.95mm. The infrared athermalized optical lens of this embodiment performs particularly well in the infrared band, especially in the 8μm-12μm band.

[0088] Figure 12 The modulation transfer function diagram of the infrared athermalized optical lens provided in this embodiment at room temperature (25°C) is shown. Figure 13 This is a modulation transfer function graph of the infrared athermalized optical lens provided in this embodiment at -40°C. Figure 14 This is a modulation transfer function diagram of the infrared athermalized optical lens provided in this embodiment at 80°C. Figure 15 This is a blur pattern of the infrared athermalized optical lens provided in this embodiment. Figures 12-15 It is known that the infrared athermalized optical lens has good imaging quality in the temperature range of -40℃ to 80℃. At a spatial frequency of 42 cycles / mm, the modulation transfer function value of the central field of view of the infrared athermalized optical lens at room temperature in the wavelength range of 8μm-12μm is greater than 90% of the diffraction limit.

[0089] The conditional expressions in Examples 1 to 3 satisfy the relationships shown in Table 7.

[0090] Table 7

[0091] Conditional expression Example 1 Example 2 Example 3 f1 / f 0.61 0.61 1.38 |f2 / f| 0.51 0.5 0.39 f3 / f 0.77 0.77 0.39 f×(n1-1) / (FNO×R1) 1.89 2.01 1.37 <![CDATA[D3 / (H×f)(mm -1 )]]> 0.27 0.21 0.24 f / H 2.74 3.66 5.08 v1-v2 61.3 61.3 248.65

[0092] In summary, Examples 1-3 demonstrate that the infrared pyro-optical lens provided in this application has excellent imaging performance in the long-wave infrared band when all lenses have no diffraction surfaces, and has broad application prospects in security, temperature measurement, automotive and other fields, especially in the automotive field.

[0093] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An infrared athermalized optical lens, characterized in that, Along the optical axis from the object side to the image side, the following are included in sequence: The first lens with positive optical power has a convex object side and a concave image side. A second lens with negative optical power has an object-side surface that is either convex or concave, and an image-side surface that is concave. A third lens with positive optical power has convex surfaces on both its object side and image side. The first lens, the second lens, and the third lens are all non-diffractive lenses, and the materials of the first lens, the second lens, and the third lens are all chalcogenide glass. The refractive index of the material of the first lens or the third lens is greater than 3.

2. The infrared athermalized optical lens according to claim 1, characterized in that, The total effective focal length f of the infrared athermalized optical lens, the refractive index n1 of the first lens, the aperture value FNO of the infrared athermalized optical lens, and the radius of curvature R1 of the object side surface of the first lens satisfy: 1.37≤f×(n1-1) / (FNO×R1)≤2.

01.

3. The infrared athermalized optical lens according to claim 1, characterized in that, The maximum effective aperture D3 of the third lens, the half-image height H of the infrared athermalized optical lens, and the total effective focal length f of the infrared athermalized optical lens satisfy: 0.2mm. -1 ≤D3 / (H×f)≤0.3mm -1 .

4. The infrared athermalized optical lens according to claim 1, characterized in that, The total effective focal length f of the infrared athermalized optical lens and the half-image height H of the infrared athermalized optical lens satisfy the following condition: 2.7 ≤ f / H ≤ 5.

1.

5. The infrared athermalized optical lens according to claim 1, characterized in that, The effective focal length f1 of the first lens and the total effective focal length f of the infrared athermalized optical lens satisfy the condition: 0.61≤f1 / f≤1.

38.

6. The infrared athermalized optical lens according to claim 1, characterized in that, The effective focal length f2 of the second lens and the total effective focal length f of the infrared athermalized optical lens satisfy the following condition: 0.39≤|f2 / f|≤0.

51.

7. The infrared athermalized optical lens according to claim 1, characterized in that, The effective focal length f3 of the third lens and the total effective focal length f of the infrared athermalized optical lens satisfy the following condition: 0.39≤f3 / f≤0.

77.

8. The infrared athermalized optical lens according to claim 1, characterized in that, The Abbe number v1 of the first lens and the Abbe number v2 of the second lens satisfy: 61.3≤v1-v2≤248.

65.

9. The infrared athermalized optical lens according to any one of claims 1-8, characterized in that, With a spatial frequency of 42 cycles / mm, the modulation transfer function of the infrared athermal optical lens at room temperature in the wavelength range of 8μm-12μm is greater than 90% of the diffraction limit.

10. The infrared athermalized optical lens according to any one of claims 1-8, characterized in that, The total effective focal length f of the infrared athermalized optical lens satisfies: 13mm≤f≤25mm.

Images