A spherical array fresnel lens, detector and security system

Abstract

The application relates to the technical field of detectors, and provides a spherical array Fresnel lens, a detector and a security system, wherein the spherical array Fresnel lens comprises a lens body, the lens body has an inner spherical surface and an outer spherical surface; a center lens sheet layer is arranged at the center of the inner spherical surface of the lens body, and the inner spherical surface of the lens body is further provided with a plurality of annular lens sheet layers; the center lens sheet layer comprises one Fresnel lens element, and the annular lens sheet layer comprises a plurality of Fresnel lens elements; the detector comprises the spherical array Fresnel lens; and the security system comprises the detector. The spherical array Fresnel lens, the detector and the security system provided by the application can be simultaneously applied to a wall-mounted installation mode and a ceiling-mounted installation mode while meeting the requirements of detection angles and detection distances.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detectors, and more particularly relates to a spherical array Fresnel lens, a detector and a security system. BACKGROUND

[0002] Most of the Fresnel lenses used by passive infrared intrusion detectors are pressed from high-density polyethylene materials, and the main function thereof is to image a heat-emitting target object on an infrared pyroelectric sensor wafer or focus the thermal infrared light (wavelength between 3 mu m-14 mu m) emitted by the heat-emitting object on the pyroelectric sensor.

[0003] The shapes of the Fresnel lenses include planar shape, hemispherical shape and aspherical shape. The planar Fresnel lenses on the market are curved into semicircular shapes and are mostly installed in a wall-hanging manner. The hemispherical Fresnel lenses are mostly installed in a ceiling-hanging manner. Under the requirements of detection angle and detection distance, the conventional Fresnel lenses are difficult to be simultaneously applicable to the wall-hanging installation manner and the ceiling-hanging installation manner, and thus need to be improved. SUMMARY

[0004] The purpose of the embodiments of the application is to provide a spherical array Fresnel lens, a detector and a security system, so as to improve the following technical problem: under the requirements of detection angle and detection distance, the conventional Fresnel lenses are difficult to be simultaneously applicable to the wall-hanging installation manner and the ceiling-hanging installation manner.

[0005] In a first aspect, the application provides a spherical array Fresnel lens, comprising a lens body, wherein the lens body has an inner spherical surface and an outer spherical surface;

[0006] The inner spherical surface of the lens body is fixed with a center lens sheet layer, and the inner spherical surface of the lens body is further provided with a plurality of annular lens sheet layers, wherein the annular lens sheet layer located in the innermost circle is arranged around the center lens sheet layer, and the annular lens sheet layer located in the adjacent outer circle is arranged around the annular lens sheet layer located in the adjacent inner circle.

[0007] The center lens sheet layer comprises one Fresnel lens element, and the annular lens sheet layer comprises a plurality of Fresnel lens elements.

[0008] In an implementable technical solution of the application, the focal length of each Fresnel lens element is smaller than the radius of curvature of the inner surface of the lens body at the position of the Fresnel lens element.

[0009] In an implementable technical solution of the application, the tooth height of the Fresnel lens element is between 0.15-0.25 mm, and the thickness of the Fresnel lens element is between 0.5-1.0 mm.

[0010] In an implementation of the present application, the inner spherical surface of the lens body is provided with three sets of annular lens sheet layers, the three sets of annular lens sheet layers are respectively a first annular lens sheet layer, a second annular lens sheet layer and a third annular lens sheet layer, and the outer periphery of the third annular lens sheet layer is aligned with the circumferential edge of the inner spherical surface of the lens body.

[0011] In an implementation of the present application, the first annular lens sheet layer includes eight equal first Fresnel lens elements, and the eight first Fresnel lens elements are uniformly and symmetrically arranged around the center point of the center lens sheet layer.

[0012] The second annular lens sheet layer includes twelve equal second Fresnel lens elements, and the twelve second Fresnel lens elements are uniformly and symmetrically arranged around the center point of the center lens sheet layer.

[0013] The third annular lens sheet layer includes twelve equal third Fresnel lens elements, and the twelve third Fresnel lens elements are uniformly and symmetrically arranged around the center point of the center lens sheet layer.

[0014] In an implementation of the present application, the lens body includes a spherical surface part and an annular mounting part, the annular mounting part is connected to the circumferential edge of the inner spherical surface of the spherical surface part, and the center of the spherical surface part is located on the central axis of the annular mounting part.

[0015] In an implementation of the present application, the annular mounting part is provided with one or more positioning grooves away from the end of the spherical surface part.

[0016] In an implementation of the present application, the annular mounting part is provided with one or more buckle holes.

[0017] In a second aspect, the present application provides a detector, which includes a mounting base, an infrared detector body and a spherical array Fresnel lens as described above, the infrared detector body is mounted on the mounting base, the infrared detector body is provided with a pyroelectric sensor, and the spherical array Fresnel lens is mounted on the end of the infrared detector body away from the mounting base.

[0018] In a third aspect, the present application provides a security system using the detector as described above.

[0019] In summary, the present application at least includes the following beneficial technical effects:

[0020] 1. The spherical surface part provided with inner and outer spherical surfaces is a fully symmetrical design, and a plurality of annular lens sheet layers are arranged around the central lens sheet layer in a circle by circle manner, which is also a symmetrical design. Therefore, whether the spherical array Fresnel lens is installed on a wall or a roof, the thermal infrared light emitted by a heat-emitting object can be focused on the center of the inner spherical surface through the lens body and the Fresnel lens element, so that the spherical array Fresnel lens can be applied to wall-mounted and ceiling-mounted installation modes at the same time, meet different use scenarios, and have stronger market competitiveness under the requirements of detection angle and detection distance.

[0021] 2. The volume, thickness and production cost of the spherical array Fresnel lens are small, thin and low under the requirements of detection angle and detection distance due to the adoption of the above layout design of the Fresnel lens element. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The structural schematic diagram of the spherical array Fresnel lens provided by the embodiments of the present application.

[0024] Figure 2 The sectional structural schematic diagram of the lens body in the embodiments of the present application.

[0025] Figure 3 The layout schematic diagram of all the Fresnel lens elements in the embodiments of the present application.

[0026] Figure 4 The structural schematic diagram of one of the Fresnel lens elements in the embodiments of the present application.

[0027] Figure 5 The distribution schematic diagram of the central lens sheet layer in the embodiments of the present application.

[0028] Figure 6 The distribution schematic diagram of the first annular lens sheet layer in the embodiments of the present application.

[0029] Figure 7 The distribution schematic diagram of the second annular lens sheet layer in the embodiments of the present application.

[0030] Figure 8 The distribution schematic diagram of the third annular lens sheet layer in the embodiments of the present application.

[0031] Figure 9A distribution diagram of Fresnel lens elements in a near-distance multi-view zone in an embodiment of the present application.

[0032] Figure 10 A distribution diagram of Fresnel lens elements in a middle-distance multi-view zone in an embodiment of the present application.

[0033] Figure 11 A distribution diagram of Fresnel lens elements in a far-distance multi-view zone in an embodiment of the present application.

[0034] Figure 12 A side view of an effective detection area of a spherical array Fresnel lens in a wall-mounted installation mode in an embodiment of the present application.

[0035] Figure 13 A top view of an effective detection area of a spherical array Fresnel lens in a wall-mounted installation mode in an embodiment of the present application.

[0036] Figure 14 A side view of an effective detection area of a spherical array Fresnel lens in a ceiling-mounted installation mode in an embodiment of the present application.

[0037] Figure 15 A top view of an effective detection area of a spherical array Fresnel lens in a ceiling-mounted installation mode in an embodiment of the present application.

[0038] Figure 16 A structure diagram of a detector in a wall-mounted installation mode in an embodiment of the present application.

[0039] Figure 17 A structure diagram of a detector in a ceiling-mounted installation mode in an embodiment of the present application.

[0040] In the drawings, various reference numerals are used to refer to the same or similar elements throughout the drawings.

[0041] 101, mounting base;

[0042] 102, infrared detector body; 21, pyroelectric sensor;

[0043] 103, spherical array Fresnel lens; 31, lens body; 311, spherical surface; 312, annular mounting portion; 3121, positioning groove; 3122, buckle hole; 32, central lens sheet layer; 33, first annular lens sheet layer; 331, first Fresnel lens element; 34, second annular lens sheet layer; 341, second Fresnel lens element; 35, third annular lens sheet layer; 351, third Fresnel lens element; 300, Fresnel tooth. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, further detailed description will be made to the present application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0045] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0046] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0047] In addition, the terms "first", "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0048] Please refer to Figures 1-17 , a spherical array Fresnel lens, a detector and a security system provided by the embodiments of the present application will be described.

[0049] The embodiments of the present application provide a spherical array Fresnel lens, please refer to Figures 1 to 3 , which comprises a lens body 31, the lens body 31 has an inner spherical surface and an outer spherical surface, the outer spherical surface is a smooth curved surface, and the inner spherical surface is formed by a Fresnel tooth machined from a convolution.

[0050] The spherical array Fresnel lens is mainly made of high-density polyethylene material, and the lens body 31 comprises an integrally formed spherical part 311 and an annular mounting part 312, the Fresnel lens element is mounted on the inner spherical surface of the spherical part 311, the annular mounting part 312 is connected to the circumferential edge of the inner spherical surface of the spherical part 311, the spherical center of the spherical part 311 is located on the central axis of the annular mounting part 312, and the outer diameter of the spherical part 311 is slightly larger than the outer diameter of the annular mounting part 312.

[0051] The end of the annular mounting portion 312 away from the spherical surface portion 311 is provided with a positioning groove 3121. The positioning groove 3121 is mainly used for clamping positioning with other mounting structures when the spherical array Fresnel lens is mounted and fixed, so that the mounting position is more accurate and the mounting process is more efficient.

[0052] In other embodiments, the number of positioning grooves 3121 can also be two, three or even more.

[0053] The annular mounting portion 312 is provided with four buckle holes 3122. The four buckle holes 3122 are uniformly and symmetrically arranged along the annular mounting portion 312, and the shape of the buckle hole 3122 is approximately square, and the four corners of the buckle hole 3122 are designed as arc corners. The buckle hole 3122 is mainly used for clamping and fixing with other mounting structures (elastic protruding structures that can be clamped into the buckle hole 3122) when the spherical array Fresnel lens is mounted and fixed, so that the mounting position is more accurate and the connection structure is more firm.

[0054] The inner spherical surface of the lens body 31 is provided with a center lens sheet layer 32, and the inner spherical surface of the lens body 31 is also provided with a plurality of annular lens sheet layers. The annular lens sheet layer located in the innermost circle is arranged around the center lens sheet layer 32, and the annular lens sheet layer located in the adjacent outer circle is arranged around the annular lens sheet layer located in the adjacent inner circle.

[0055] Referring to Figure 3 and Figure 5 , the center lens sheet layer 32 includes one Fresnel lens element, and the annular lens sheet layer includes a plurality of Fresnel lens elements. The Fresnel lens element and the lens body 31 are integrally injection molded. The focal length of each Fresnel lens element is less than the radius of curvature of the inner surface of the lens body 31 at the position of the Fresnel lens element.

[0056] The tooth height of the Fresnel tooth 300 is between 0.15-0.25mm, and in this embodiment, the tooth height of the Fresnel tooth 300 is preferably 0.2mm. The thickness of the Fresnel lens element is between 0.5-1.0mm, and in this embodiment, the thickness of the Fresnel lens element is preferably 0.8mm. Under the condition of allowable strength, the thinner the thickness of the Fresnel lens element, the better the refraction and condensation effect.

[0057] In this embodiment, the annular lens sheet layer is provided with three groups, which are the first annular lens sheet layer 33, the second annular lens sheet layer 34 and the third annular lens sheet layer 35. The outer periphery of the third annular lens sheet layer 35 is aligned with the inner spherical surface periphery of the lens body 31.

[0058] In other embodiments, the number of annular lens sheet layers can be two, four, five or even more, which can be designed according to the size, size and functional requirements of the spherical array Fresnel lens.

[0059] Referring to Figure 2 and Figure 4 , the outer surface of the Fresnel lens element is attached to the inner spherical surface of the lens body 31, and the inner surface of the Fresnel lens element is provided with a plurality of concentrically arranged Fresnel teeth 300. Under the action of the Fresnel teeth 300, the thermal infrared light is refracted by the Fresnel lens element and converges to the spherical center position of the inner spherical surface, which is just provided with a pyroelectric sensor (see Figure 16 or Figure 17 ).

[0060] Referring to Figure 3 and Figure 6 , the first annular lens sheet layer 33 includes eight equal first Fresnel lens elements 331, which are uniformly and symmetrically arranged around the center point of the center lens sheet layer 32.

[0061] Referring to Figure 3 and Figure 7 , the second annular lens sheet layer 34 includes twelve equal second Fresnel lens elements 341, which are uniformly and symmetrically arranged around the center point of the center lens sheet layer 32.

[0062] Referring to Figure 3 and Figure 8 , the third annular lens sheet layer 35 includes twelve equal third Fresnel lens elements 351, which are uniformly and symmetrically arranged around the center point of the center lens sheet layer 32.

[0063] In this embodiment, when the spherical array Fresnel lens is in a wall-mounted installation mode, all the Fresnel lens elements are divided into three multi-view areas: near multi-view area, middle multi-view area, and far multi-view area.

[0064] Referring to Figure 3 and Figure 9 , all the Fresnel lens elements of the far multi-view area are on a straight line, and include one Fresnel lens element of the center lens sheet layer 32, two first Fresnel lens elements 331 of the first annular lens sheet layer 33, two second Fresnel lens elements 341 of the second annular lens sheet layer 34, and two third Fresnel lens elements 351 of the third annular lens sheet layer 35.

[0065] Two of the first Fresnel lens elements 331 are symmetrically arranged on both sides of the Fresnel lens element of the center lens sheet layer 32, two of the second Fresnel lens elements 341 are symmetrically arranged on both sides of the Fresnel lens element of the center lens sheet layer 32, and two of the third Fresnel lens elements 351 are symmetrically arranged on both sides of the Fresnel lens element of the center lens sheet layer 32.

[0066] Referring to Figure 3 andFigure 10 , all the Fresnel lens elements of the middle-distance multi-view area are divided into two groups and respectively located on both sides of all the Fresnel lens elements of the far-distance multi-view area, the Fresnel lens elements of the middle-distance multi-view area include all the first Fresnel lens elements 331 in the first annular lens sheet layer 33 except those belonging to the far-distance multi-view area, all the second Fresnel lens elements 341 in the second annular lens sheet layer 34 except those belonging to the far-distance multi-view area, and the four third Fresnel lens elements 351 in the third annular lens sheet layer 35 close to the far-distance multi-view area.

[0067] With reference to Figure 3 and Figure 11 , all the Fresnel lens elements of the near-distance multi-view area are divided into two groups and respectively symmetrically and spacedly arranged on both sides of all the Fresnel lens elements of the far-distance multi-view area, the Fresnel lens elements of the near-distance multi-view area include the remaining six third Fresnel lens elements 351 in the third annular lens sheet layer 35, and three third Fresnel lens elements 351 form a group.

[0068] In the embodiment, when the spherical array Fresnel lens is in the wall-mounted installation mode, the spherical array Fresnel lens is at a position with a height of 2.2 meters, the detection range of the spherical array Fresnel lens is 90 degrees in the overhead view angle, the side view distance is 1-8 meters and is in the shape of a three-dimensional sector, specifically, FIG. 6 is a side view of the effective detection area of the spherical array Fresnel lens in the above state, and FIG. 7 is a top view of the effective detection area of the spherical array Fresnel lens in the above state. Figure 12 In the embodiment, when the spherical array Fresnel lens is in the wall-mounted installation mode, the spherical array Fresnel lens is at a position with a height of 2.2 meters, the detection range of the spherical array Fresnel lens is 90 degrees in the overhead view angle, the side view distance is 1-8 meters and is in the shape of a three-dimensional sector, specifically, FIG. 6 is a side view of the effective detection area of the spherical array Fresnel lens in the above state, and FIG. 7 is a top view of the effective detection area of the spherical array Fresnel lens in the above state. Figure 13 In the embodiment, when the spherical array Fresnel lens is in the wall-mounted installation mode, the spherical array Fresnel lens is at a position with a height of 2.2 meters, the detection range of the spherical array Fresnel lens is 90 degrees in the overhead view angle, the side view distance is 1-8 meters and is in the shape of a three-dimensional sector, specifically, FIG. 6 is a side view of the effective detection area of the spherical array Fresnel lens in the above state, and FIG. 7 is a top view of the effective detection area of the spherical array Fresnel lens in the above state.

[0069] In the embodiment, when the spherical array Fresnel lens is in the wall-mounted installation mode, the spherical array Fresnel lens is at a position with a height of 2.2 meters, the detection range of the spherical array Fresnel lens is 90 degrees in the overhead view angle, the side view distance is 1-8 meters and is in the shape of a three-dimensional sector, specifically, FIG. 6 is a side view of the effective detection area of the spherical array Fresnel lens in the above state, and FIG. 7 is a top view of the effective detection area of the spherical array Fresnel lens in the above state. Figure 14 In the embodiment, when the spherical array Fresnel lens is in the wall-mounted installation mode, the spherical array Fresnel lens is at a position with a height of 2.2 meters, the detection range of the spherical array Fresnel lens is 90 degrees in the overhead view angle, the side view distance is 1-8 meters and is in the shape of a three-dimensional sector, specifically, FIG. 6 is a side view of the effective detection area of the spherical array Fresnel lens in the above state, and FIG. 7 is a top view of the effective detection area of the spherical array Fresnel lens in the above state. Figure 15 In the embodiment, when the spherical array Fresnel lens is in the wall-mounted installation mode, the spherical array Fresnel lens is at a position with a height of 2.2 meters, the detection range of the spherical array Fresnel lens is 90 degrees in the overhead view angle, the side view distance is 1-8 meters and is in the shape of a three-dimensional sector, specifically, FIG. 6 is a side view of the effective detection area of the spherical array Fresnel lens in the above state, and FIG. 7 is a top view of the effective detection area of the spherical array Fresnel lens in the above state.

[0070] The working principle of the spherical array Fresnel lens provided in the application is as follows:

[0071] The spherical surface part 311 provided with the inner spherical surface and the outer spherical surface is a fully symmetrical design, and a plurality of annular lens sheet layers are arranged around the central lens sheet layer 32 in a circle by circle manner, which is also a symmetrical design. The inner surface of the Fresnel lens element is provided with a plurality of concentrically arranged Fresnel teeth 300. Therefore, no matter whether the spherical array Fresnel lens is installed on a wall or a roof, the thermal infrared light emitted by a heat object can pass through the lens body 31 and the Fresnel lens element and then be focused on the center of the inner spherical surface. The pyroelectric sensor arranged at the center of the inner spherical surface divides the detection area into a plurality of light areas and dark areas, so that the moving object entering the detection area can generate a change pyroelectric infrared signal on the pyroelectric sensor in the form of temperature change.

[0072] Compared with the prior art, the spherical array Fresnel lens provided in the application has the following predictable technical effects:

[0073] Under the requirements of detection angle and detection distance, the spherical array Fresnel lens can be simultaneously applied to wall-mounted installation and ceiling-mounted installation, can meet different use scenarios, has stronger market competitiveness, and has smaller volume, thinner thickness and lower manufacturing cost due to the layout design of the Fresnel lens element.

[0074] The application also provides a detector, please refer to Figure 16 and Figure 17 , which comprises a mounting base 101, an infrared detector body 102 and the spherical array Fresnel lens 103 as described above. The infrared detector body 102 is mounted on the mounting base 101. The infrared detector body 102 is provided with a pyroelectric sensor 21. The spherical array Fresnel lens 103 is mounted on the end of the infrared detector body 102 away from the mounting base. The mounting mode of the spherical array Fresnel lens 103 is the common buckle connection.

[0075] The infrared detector body 102 and the spherical array Fresnel lens 103 jointly form a substantially spherical center structure, Figure 16 is a structural schematic view of the detector in a wall-mounted installation mode, Figure 17 is a structural schematic view of the detector in a ceiling-mounted installation mode.

[0076] The detector can be a passive infrared intrusion detector or an infrared microwave comprehensive detector.

[0077] The application also provides a security system using the detector as described above.

[0078] The above only describes the preferred embodiments of the application and is not used to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A spherical array Fresnel lens, characterized in that, Includes a lens body, the lens body having an inner spherical surface and an outer spherical surface; A central lens layer is provided at the center of the inner spherical surface of the lens body. The inner spherical surface of the lens body is also provided with multiple sets of annular lens layers. The annular lens layers located in the innermost ring are arranged around the central lens layer, and the annular lens layers in the adjacent outer ring are arranged around the annular lens layers in the adjacent inner ring. The central lens layer includes a Fresnel lens element, and the annular lens layer includes multiple Fresnel lens elements; The inner spherical surface of the lens body is provided with three sets of annular lens layers, namely a first annular lens layer, a second annular lens layer and a third annular lens layer, and the outer periphery of the third annular lens layer is aligned with the periphery of the inner spherical surface of the lens body. When the spherical array Fresnel lens is wall-mounted, all Fresnel lens elements are divided into three multi-view zones: near-field multi-view zone, medium-field multi-view zone, and far-field multi-view zone; All Fresnel lens elements in the long-range multi-view area are arranged in a straight line, and include one Fresnel lens element in the central lens layer, two first Fresnel lens elements in the first annular lens layer, two second Fresnel lens elements in the second annular lens layer, and two third Fresnel lens elements in the third annular lens layer; wherein the two first Fresnel lens elements are symmetrically arranged on both sides of the Fresnel lens element in the central lens layer, the two second Fresnel lens elements are symmetrically arranged on both sides of the Fresnel lens element in the central lens layer, and the two third Fresnel lens elements are symmetrically arranged on both sides of the Fresnel lens element in the central lens layer; All Fresnel lens elements in the mid-range multi-view zone are divided into two groups and located on both sides of all Fresnel lens elements in the far-range multi-view zone. The Fresnel lens elements in the mid-range multi-view zone include all first Fresnel lens elements in the first annular lens layer excluding those belonging to the far-range multi-view zone, all second Fresnel lens elements in the second annular lens layer excluding those belonging to the far-range multi-view zone, and four third Fresnel lens elements in the third annular lens layer that are close to the far-range multi-view zone. All Fresnel lens elements in the near-field multi-view zone are divided into two groups and are symmetrically spaced on both sides of all Fresnel lens elements in the far-field multi-view zone. The Fresnel lens elements in the near-field multi-view zone include the remaining six third Fresnel lens elements in the third annular lens layer, and three third Fresnel lens elements form a group.

2. A spherical array Fresnel lens as described in claim 1, characterized in that: The focal length of each Fresnel lens element is less than the radius of curvature of the inner surface of the lens body at the location of the Fresnel lens element.

3. A spherical array Fresnel lens as described in claim 1, characterized in that: The tooth height of the Fresnel lens element is between 0.15 and 0.25 mm, and the thickness of the Fresnel lens element is between 0.5 and 1.0 mm.

4. A spherical array Fresnel lens as described in claim 1, characterized in that: The first annular lens layer includes eight equal first Fresnel lens elements, which are arranged in a uniform and symmetrical array around the center point of the central lens layer. The second annular lens layer includes twelve equal second Fresnel lens elements, which are arranged in a uniform and symmetrical array around the center point of the central lens layer; The third annular lens layer includes twelve equal third Fresnel lens elements, which are arranged in a uniform and symmetrical array around the center point of the central lens layer.

5. A spherical array Fresnel lens as described in any one of claims 1 to 4, characterized in that: The lens body includes a spherical part and an annular mounting part. The annular mounting part is connected to the periphery of the inner spherical surface of the spherical part, and the center of the spherical part is located on the central axis of the annular mounting part.

6. A spherical array Fresnel lens as described in claim 5, characterized in that: The annular mounting portion has one or more positioning grooves at its end away from the spherical surface.

7. A spherical array Fresnel lens as described in claim 5, characterized in that: The annular mounting part is provided with one or more snap-fit ​​holes.

8. A detector, characterized in that: The device includes a mounting base, an infrared detector body, and a spherical array Fresnel lens as described in any one of claims 1 to 7. The infrared detector body is mounted on the mounting base, and a pyroelectric sensor is disposed within the infrared detector body. The spherical array Fresnel lens is mounted at the end of the infrared detector body away from the mounting base.

9. A security system, characterized in that: The detector described in claim 8 is used.

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