An infrared lens with controllable aperture and its working method

Abstract

This invention provides an infrared lens with a controllable aperture and its operating method. The lens comprises a first lens G101, a second lens G102, a variable aperture STO, a third lens G103, and a fourth lens G104 arranged sequentially from front to back along the incident light path. The first lens G101 is a positive meniscus lens with positive optical power, the second lens G102 is a positive meniscus lens with positive optical power, the third lens G103 is a positive meniscus lens with positive optical power, and the fourth lens G104 is a window lens. This invention is not only compact and reasonable in structure, but also effectively solves the problem of existing infrared detectors losing their observation capability when damaged, ensuring that the lens still has high definition under high heat radiation conditions, and further enhancing the adaptability of an infrared lens with a controllable aperture to harsh environments.

Description

Technical Field

[0001] This invention relates to an infrared lens with controllable aperture and its working method. Background Technology

[0002] Infrared optical imaging requires meeting certain stringent conditions, particularly the ability to directly observe high-temperature targets. However, observing high-temperature targets means that the infrared system must observe targets with high thermal radiation energy sources. This implies that the energy radiated by the target will exceed the energy threshold of the infrared detector. If it exceeds this threshold, the detector will be damaged and lose its observation capability. Most infrared systems do not fully meet this requirement, posing a risk of severely impacting the lens's observation capabilities, limiting the effectiveness of infrared imaging, and potentially creating safety hazards. Summary of the Invention

[0003] In view of these shortcomings, the present invention makes improvements to address the problems existing in the prior art. The technical problem to be solved by the present invention is to provide an infrared lens with controllable aperture and its working method, which is not only compact and reasonable in structure, but also has the function of changing the F number, realizing continuous change of the F number from 1.0 to 3.0. This effectively solves the problem of existing infrared detectors being damaged and losing their observation capabilities, ensuring that the lens still has high definition under high heat radiation conditions, and further enhancing the adaptability of an infrared lens with controllable aperture to harsh environments.

[0004] The present invention is implemented using the following scheme: an infrared lens with controllable aperture, the lens comprising a first lens G101, a second lens G102, a variable aperture STO, a third lens G103, and a fourth lens G104 arranged sequentially from front to back along the incident light path; the first lens G101 is a positive meniscus lens with positive optical power, the second lens G102 is a positive meniscus lens with positive optical power, the third lens G103 is a positive meniscus lens with positive optical power, and the fourth lens G104 is a window lens.

[0005] Furthermore, the object-side surface of the first lens G101 is convex and the image-side surface is concave; the object-side surface of the second lens G102 is convex and the image-side surface is concave; the object-side surface of the third lens G103 is concave and the image-side surface is convex; and both the object-side surface and the image-side surface of the fourth lens G104 are planar.

[0006] Furthermore, the air gap between the first lens G101 and the second lens G102 is 1.9mm to 2.6mm, the air gap between the second lens G102 and the variable stop STO is 2.5mm to 3.5mm, the air gap between the variable stop STO and the third lens G103 is 1.60mm to 2.8mm, and the air gap between the third lens G103 and the fourth lens G104 is 5.0mm to 6.2mm.

[0007] Furthermore, the focal length of the lens is f, and the focal lengths of the first lens G101, the second lens G102, and the third lens G103 are f, respectively. A f B f C , where f A f B f C It satisfies the following ratio with f: 2.0 <f A <5.5, 20.0 <f B <26.0, 12.0 <f C <15.0, 0.18<|f A / f|<0.32, 1.40<|f B / f|<1.90, 0.85<|f C / f|<1.15.

[0008] Furthermore, the first lens G101 satisfies the following relationship: N d ≥4.00, V d ≤820; The second lens G102 satisfies the following relationship: N d ≥2.40, V d ≤154; The third lens G103 satisfies the following relationship: N d ≥2.40, V d ≤154; The fourth lens G104 satisfies the following relationship: N d ≥4.00, V d ≤820; where N d V is the refractive index. d Let be Abbe's constant.

[0009] Furthermore, the object-side surface of the first lens G101 and the image-side surface of the second lens G102 are both even-order aspherical surfaces, and the surface shape equations of even-order aspherical surfaces are as follows:

[0010]

[0011] Where Z is the height difference between the aspherical surface and its vertex when the aspherical surface reaches a position of height r along the optical axis; c = 1 / r, where r represents the paraxial radius of curvature of the mirror, and k is the conic coefficient, A2, A4, A6, A8, A 10 A 12 It is expressed as a higher-order aspheric coefficient.

[0012] Further, the lens satisfies: IMGH / f < 0.49, 0.86 < tanω / (IMGH / f) < 1.35; where IMGH is the semi-image height of the detector used by the infrared lens, f is the focal length of the infrared lens, and ω is the semi-field angle of the infrared lens.

[0013] Further, one of the first lens G101, the second lens G102, and the third lens G103 is made of a chalcogenide lens.

[0014] Further, the overall optical length TTA of the lens satisfies: TTL < 35 mm.

[0015] A working method of an infrared lens with controllable aperture: Light rays pass through the first lens G101, the second lens G102, the variable aperture STO, the third lens G103, and the fourth lens G104 in sequence from the object side and form an image on the imaging surface.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention is not only compact and reasonable in structure, but also effectively solves the problem that the existing infrared detector is damaged and loses the observation ability, ensures that the lens still has high clarity under high heat radiation conditions, and further enhances the applicability of an infrared lens with controllable aperture in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic optical structure diagram of an embodiment of the present invention;

[0018] Figure 2 is a MTF value diagram of an embodiment of the present invention; <000A091>

[0019] Figure 3 is a spot diagram of an embodiment of the present invention;

[0020] Figure 4 is a field curvature and distortion diagram of an embodiment of the present invention;

[0021] Figure 5 is a variable aperture structure diagram of an embodiment of the present invention.

[0022] In the figure: G101 - the first lens; G102 - the second lens; G103 - the third lens; G104 - the fourth lens; STO - the variable aperture surface. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] like Figure 1 As shown, this embodiment provides an infrared lens with a controllable aperture. The lens consists of a first lens G101, a second lens G102, a variable aperture STO, a third lens G103, and a fourth lens G104 arranged sequentially from front to back along the incident light path. The first lens G101 is a positive meniscus lens with positive optical power, the second lens G102 is a positive meniscus lens with positive optical power, the third lens G103 is a positive meniscus lens with positive optical power, and the fourth lens G104 is a window lens. The variable aperture is a prior art technology.

[0027] In this embodiment, the object-side surface of the first lens G101 is convex and the image-side surface is concave; the object-side surface of the second lens G102 is convex and the image-side surface is concave; the object-side surface of the third lens G103 is concave and the image-side surface is convex; and both the object-side surface and the image-side surface of the fourth lens G104 are planar.

[0028] In this embodiment, the air gap between the first lens G101 and the second lens G102 is 1.9mm to 2.6mm, the air gap between the second lens G102 and the variable aperture STO is 2.5mm to 3.5mm, the air gap between the variable aperture STO and the third lens G103 is 1.60mm to 2.8mm, and the air gap between the third lens G103 and the fourth lens G104 is 5.0mm to 6.2mm.

[0029] In this embodiment, the focal length of the lens is f, and the focal lengths of the first lens G101, the second lens G102, and the third lens G103 are f, respectively. A f B f C , where f A f B f C It satisfies the following ratio with f: 2.0 <f A <5.5, 20.0 <f B <26.0, 12.0 <f C <15.0, 0.18<|f A / f|<0.32, 1.40<|f B / f | < 1.90, 0.85 < | f C / f | < 1.15

[0030] In this embodiment, the first lens G101 satisfies the relational expression: N d ≥ 4.00, V d ≤ 820; the second lens G102 satisfies the relational expression: N d ≥ 2.40, V d ≤ 154; the third lens G103 satisfies the relational expression: N d ≥ 2.40, V d ≤ 154; the fourth lens G104 satisfies the relational expression: N d ≥ 4.00, V d ≤ 820; where N d is the refractive index and V d is the Abbe number

[0031] In this embodiment, the object side surface of the first lens G101 and the image side surface of the second lens G102 are both even aspherical surfaces. Considering the characteristics of the infrared optical system that require aberration correction, setting the even aspherical surfaces specifically according to the different systems can well control the aberration of the infrared optical system. The surface equation of the even aspherical surface is as follows:

[0032]

[0033] where Z is the height loss from the vertex of the aspherical surface when the aspherical surface reaches a position with a height of r along the optical axis direction; c = 1 / r, r represents the paraxial curvature radius of the mirror surface, k is the conic coefficient, and A2, A4, A6, A8, A 10 、A 12 represent the high-order aspherical coefficients. The table of high-order aspherical coefficients is shown in the following table:

[0034] Face number A4 A6 A8 A10 A12 S1 -1.383E-06 -7.337E-07 4.84E-09 -2.524E-12 2.51E-15 S4 4.6523E-05 2.78E-07 -1.2201E-08 -1.61E-10 -1.164E-12

[0035] In this embodiment, the lens satisfies: IMGH / f < 0.49, 0.86 < tanω / (IMGH / f) < 1.35; where IMGH is the semi-image height of the detector used by the infrared lens, f is the focal length of the infrared lens, and ω is the semi-field angle of the infrared lens

[0036] In this embodiment, one of the first lens G101, the second lens G102, and the third lens G103 uses a chalcogenide lens to meet the requirement of the infrared system for being moldable; it can reduce the cost of mass production, increase production efficiency, and improve the accuracy of the lens surface shape

[0037] In this embodiment, the overall optical length TTA of the lens satisfies: TTL < 35 mm

[0038] In this embodiment, the above-mentioned proportional conditions are met, which allows for reasonable correction and balance of aberrations in the optical system within the wavelength range of 8–12 μm. At 42 lp / mm, all MTFs of this optical system are greater than 0.32 lp / mm, approaching the diffraction limit, resulting in high resolution and good imaging quality.

[0039] In this embodiment, the first lens, the second lens, the third lens, and the fourth lens constitute an optical element parameter summary table, which can meet the following technical specifications:

[0040] 1. Focal length 13.5mm;

[0041] 2. The F-number is 1.0-3.0;

[0042] 3. Field of view 2ω: 41.70°;

[0043] 4. Matching detector 640*51212μm.

[0044] Detailed parameters are shown in the table below; where lenses G101, G102, G103, and G104 correspond to the first, second, third, and fourth lenses, respectively, and S1, S2, S3… are labeled sequentially to represent the first, second, third, and fourth lenses, corresponding to the surface parameters from left to right along the light incident direction. The intervals indicate the distance between the center of the current surface and the center of the next surface.

[0045]

[0046] A working method of an infrared lens with a controllable aperture: light rays pass sequentially from the object side through the first lens G101, the second lens G102, the variable aperture STO, the third lens G103, and the fourth lens G104 to form an image on the imaging surface.

[0047] Modulation transfer function (MTF) can comprehensively, objectively, and effectively evaluate imaging optical systems, and is a primary means of evaluating the image quality of optical systems. From Figure 2 , Figure 3 The MTF and dot plot curves show that the MTF curve of the system does not decrease significantly in each field of view and is relatively concentrated. The MTF curves of different fields of view are very similar. At a frequency of 42.0 cy / mm, the transfer functions of each color light and each field of view are greater than 0.32. The MTF of most fields of view is greater than 0.40. The dot plots of each field of view are relatively uniform.

[0048] Figure 4 The diagram shows the field curvature and distortion of the optical imaging lens in this embodiment. The field curvature is well controlled, with all field curvatures within ±0.05mm, which can effectively ensure the overall clarity of the image.

[0049] In this embodiment, light rays pass sequentially from left to right through the first lens, the second lens, the third lens, and the fourth lens before forming an image on the detector target surface. This invention is not only compact and rationally structured, but also effectively solves the problem of existing infrared detectors losing their observation capabilities due to damage, ensuring that the lens maintains high clarity even under high thermal radiation conditions, further enhancing the adaptability of an infrared lens with controllable aperture to harsh environments.

[0050] In this embodiment, all lenses are made of fully refractive glass. The fully refractive glass design, combined with aspherical surfaces, results in an optical TTL of less than 35mm, leading to a compact overall lens size. Furthermore, the lens utilizes the material's dispersion characteristics for positive optical power design, making it easy to install and use. It is suitable for 640x512, 12μm camera modules and ensures high definition even under harsh high-temperature conditions, further enhancing the adaptability of an aperture-controlled infrared lens to harsh environments.

[0051] In this embodiment, the lens employs a first lens, a second lens, and a third lens. It uses aspherical elements combined with ordinary glass in a positive, positive, positive optical power combination to achieve advanced aberration correction. The addition of chalcogenide materials can meet the requirements for molding this infrared system.

[0052] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0053] If this document uses terms such as "first" or "second" to specify components, those skilled in the art should understand that:

[0054] The use of “first” and “second” is merely for the purpose of distinguishing parts in description. Unless otherwise stated, the above words have no special meaning.

[0055] If this invention discloses or relates to components or structural parts that are fixedly connected to each other, then, unless otherwise stated, a fixed connection can be understood as: a fixed connection that can be detached (e.g., using bolts or screws), or a fixed connection that cannot be detached (e.g., riveting, welding). Of course, a fixed connection can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0056] Furthermore, the orientations or positional relationships used in any of the technical solutions disclosed in this invention above to indicate positional relationships, such as "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this patent. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent. Unless otherwise stated, the terms used to indicate shape in any of the technical solutions disclosed in this invention above are also not applicable.

[0057] Its meaning includes shapes that are similar to, analogous to, or close to it.

[0058] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. An infrared lens with controllable aperture, characterized in that, The lens consists of a first lens G101, a second lens G102, an aperture stop STO, a third lens G103, and a fourth lens G104, which are arranged in sequence along the incident optical path from front to back; the first lens G101 is a positive meniscus lens with a positive focal power, the second lens G102 is a positive meniscus lens with a positive focal power, the third lens G103 is a positive meniscus lens with a positive focal power, and the fourth lens G104 is a window lens; The focal length of the lens is f, and the focal lengths of the first lens G101, the second lens G102, and the third lens G103 are f, respectively. A f B f C , where f A f B f C It satisfies the following ratio with f: 2.0 <f A <5.5, 20.0 <f B <26.0, 12.0 <f C <15.0, 0.18<|f A / f|<0.32, 1.40<|f B / f|<1.90, 0.85<|f C / f|<1.15; The first lens G101 satisfies the following relationship: N d ≥4.00, V d ≤820; The second lens G102 satisfies the following relationship: N d ≥2.40, V d ≤154; The third lens G103 satisfies the following relationship: N d ≥2.40, V d ≤154; The fourth lens G104 satisfies the following relationship: N d ≥4.00, V d ≤820; where N d V is the refractive index. d It is Abbe's constant; The infrared lens has a focal length of 13.5 mm and a field angle 2ω: 41.70°.

2. The infrared lens with controllable aperture according to claim 1, characterized in that, The object side of the first lens G101 is convex, the image side is concave, the object side of the second lens G102 is convex, the image side is concave, the object side of the third lens G103 is concave, the image side is convex, and the object side and the image side of the fourth lens G104 are both flat.

3. The infrared lens with controllable aperture according to claim 2, characterized in that, The air gap between the first lens G101 and the second lens G102 is 1.9 mm to 2.6 mm, the air gap between the second lens G102 and the aperture stop STO is 2.5 mm to 3.5 mm, the air gap between the aperture stop STO and the third lens G103 is 1.6.0 to 2.8 mm, and the air gap between the third lens G103 and the fourth lens G104 is 5.0 mm to 6.2 mm.

4. The infrared lens with controllable aperture according to claim 3, characterized in that, The object side of the first lens G101 and the image side of the second lens G102 are both even aspherical surfaces, and the surface shape equation of the even aspherical surface is as follows: Where Z is the height difference between the aspherical surface and its vertex when the aspherical surface reaches a position of height r along the optical axis; c = 1 / r, where r represents the paraxial radius of curvature of the mirror, and k is the conic coefficient, A2, A4, A6, A8, A 10 A 12 It is expressed as a higher-order aspheric coefficient.

5. The infrared lens with controllable aperture according to claim 4, characterized in that, The lens satisfies: IMGH / f < 0.49, 0.86 < tanω / (IMGH / f) < 1.35; where, IMGH is the semi-image height of the detector used by the infrared lens, f is the focal length of the infrared lens, and ω is the semi-field angle of the infrared lens.

6. The infrared lens with controllable aperture according to claim 5, characterized in that, One of the first lens G101, the second lens G102, and the third lens G103 is made of a chalcogenide lens.

7. The aperture-controlled infrared lens according to claim 6, characterized in that, The overall optical length TTA of the lens satisfies: TTL < 35 mm.

8. A method for operating an infrared lens with a controllable aperture, comprising using an infrared lens with a controllable aperture as described in claim 7, characterized in that, Light passes through the first lens G101, the second lens G102, the aperture stop STO, the third lens G103, and the fourth lens G104 in sequence from the object side and forms an image on the imaging surface.

Images