A compact visible wide-angle athermalized lens

Abstract

The application discloses a compact visible wide-angle athermalization lens, which comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens in sequence along the direction of light path propagation; the first lens is a negative meniscus plastic lens, both surfaces of which are even aspheric surfaces; the second lens is a positive meniscus plastic lens, both surfaces of which are even aspheric surfaces; the third lens is a positive diopter glass lens, both surfaces of which are standard spherical surfaces; the fourth lens is a negative diopter plastic lens, both surfaces of which are even aspheric surfaces; and the fifth lens is a positive diopter plastic lens, both surfaces of which are even aspheric surfaces. The lens is short in length and light in weight, and belongs to a wide-angle lens between a standard lens and a fisheye lens in terms of field of view and focal length; the lens can keep the image plane stable within a temperature difference range of -20 degrees to 60 degrees without focusing adjustment, and the pictures in daytime and at night have good co-focusing property, so that the lens can meet the needs of the current market for monitoring lenses.

Description

Technical Field

[0001] This invention relates to a compact visible-band wide-angle heat-absorbing lens, belonging to the field of optical lens technology. Background Technology

[0002] With increasing demand for security, surveillance cameras are appearing more and more frequently in people's lives. The rapid development of science and technology and the widespread use of surveillance cameras have led to increasingly higher market requirements. Compact structures, good temperature performance, achromatic performance, and wide-angle surveillance cameras that can be mass-produced using molding technology have become urgent market demands.

[0003] While existing surveillance lenses have undergone varying degrees of improvement, they still suffer from drawbacks such as lack of heat dissipation or inability to meet field-of-view requirements. They fail to adequately meet customers' demands for small size and high performance. For example, patent application number 201110307278X discloses a surveillance lens with an overall field of view of 121° and a relatively long overall length of 22.5mm. Patent application number 202210226947 9 discloses a surveillance lens and module with a field of view of only 78° and a total length of 19.7mm, and it lacks heat dissipation functionality. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a compact visible-band wide-angle heat-dissipating lens with a length of only 13.4 mm, a full field of view of 155°, and an image plane diameter of 6.5 mm. It can maintain image plane stability without focusing within a temperature range of -20 degrees to +60 degrees, resulting in good confocality for both daytime and nighttime images. It can also be mass-produced through molding.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A compact visible-band wide-angle heat-reducing lens includes a first lens, a second lens, an aperture, a third lens, a fourth lens, and a fifth lens connected in sequence along the optical path propagation direction;

[0007] The first lens is a negative meniscus plastic lens with both surfaces being even-numbered aspherical surfaces; the second lens is a positive meniscus plastic lens with both surfaces being even-numbered aspherical surfaces; the third lens is a positive diopter glass lens with both surfaces being standard spherical surfaces; the fourth lens is a negative diopter plastic lens with both surfaces being even-numbered aspherical surfaces; and the fifth lens is a positive diopter plastic lens with both surfaces being even-numbered aspherical surfaces.

[0008] The aforementioned lens comprises five lenses, including four aspherical plastic lenses and one standard glass lens. The first, second, fourth, and fifth lenses are all made of plastic and have an even number of aspherical surfaces. The third lens is made of glass and has a standard spherical surface.

[0009] This invention is a heat-dissipating wide-angle lens with a field of view and focal length between that of a standard lens and a fisheye lens, which can meet the current market demand for surveillance lenses.

[0010] The aforementioned lens has a passive heat dissipation function, which can maintain image quality without focusing within a temperature range of -20 degrees to 60 degrees.

[0011] To improve image quality, the first lens is made of T62R_2017 material; the second lens is made of E48R material; the third lens is made of H-FK61 material; the fourth lens is made of EP9000 material; and the fifth lens is made of E48R material.

[0012] To balance miniaturization and image quality, the center-to-center spacing between the first and second lenses is 2.2 ± 0.2 mm, between the second and third lenses is 0.2 ± 0.2 mm, between the third and fourth lenses is 1.8 ± 0.2 mm, and between the fourth and fifth lenses is 0.1 ± 0.2 mm. The center thickness of the first lens is 0.8 ± 0.2 mm, the second lens is 1.6 ± 0.2 mm, the third lens is 1.2 ± 0.2 mm, the fourth lens is 0.6 ± 0.2 mm, and the fifth lens is 1.5 ± 0.2 mm.

[0013] Along the direction of light propagation, the two sides of the first lens are the first incident surface and the first exit surface, the two sides of the second lens are the second incident surface and the second exit surface, the two sides of the third lens are the third incident surface and the third exit surface, the two sides of the fourth lens are the fourth incident surface and the fourth exit surface, and the two sides of the fifth lens are the fifth incident surface and the fifth exit surface.

[0014] To further improve image quality, the first incident surface is convex with a radius of curvature of 106.478±0.002 mm; the first exit surface is concave with a radius of curvature of 1.754±0.002 mm; the second incident surface is concave with a radius of curvature of -4.943±0.002 mm; the second exit surface is convex with a radius of curvature of -4.468±0.002 mm; and the third incident surface is convex with a radius of curvature of 7.668±0.002 mm. The third exit surface is convex with a radius of curvature of -2.745±0.002mm; the fourth incident surface is concave with a radius of curvature of 23.772±0.002mm; the fourth exit surface is concave with a radius of curvature of 3.296±0.002mm; the fifth incident surface is convex with a radius of curvature of 6.334±0.002mm; the fifth exit surface is convex with a radius of curvature of -3.261±0.002mm.

[0015] The center of the fourth incident surface is convex, the spherical curvature is positive, it has an aspherical coefficient, and the whole surface is concave.

[0016] As one preferred implementation, the optical aperture of the first incident surface is 7.6±0.1mm, and the optical aperture of the first exit surface is 3.4±0.1mm; the optical aperture of the second incident surface is 3.1±0.1mm, and the optical aperture of the second exit surface is 2.7±0.1mm; the optical aperture of the third incident surface is 2.2±0.1mm, and the optical aperture of the third exit surface is 3.0±0.1mm; the optical aperture of the fourth incident surface is 4.0±0.1mm, and the optical aperture of the fourth exit surface is 4.6±0.1mm; the optical aperture of the fifth incident surface is 4.6±0.1mm, and the optical aperture of the fifth exit surface is 4.8±0.1mm.

[0017] The lens has a focal length of 2.4mm, an F-number of 2.5, and a field of view of 155°; its overall length is less than 13.4mm, and its overall optical diameter is less than 8mm. It can maintain image quality without focusing within a temperature range of -20°C to 60°C.

[0018] The relative illumination of the aforementioned lens is greater than or equal to 0.5 across the entire field of view, and the angle between the principal ray and the detector is less than 20 degrees across the entire field of view. Its RMS spot size is less than 10 μm across the entire field of view, and its MTF is greater than 0.48 across the entire field of view at 83.5 line pairs per millimeter, and greater than 0.09 across the entire field of view at 167 line pairs per millimeter.

[0019] The optical components of the aforementioned lens weigh only 0.18 grams, achieving lightweight design.

[0020] Any techniques not mentioned in this invention are based on existing technologies.

[0021] This invention relates to a compact visible-band wide-angle heat-dissipating lens, composed of four plastic lenses and one glass lens. It is short and lightweight, with an overall length of less than 13.4 mm and an overall optical diameter of less than 8 mm. It has a full field of view of 155° and an image plane diameter of 6.5 mm. Its field of view and focal length fall between those of a standard lens and a fisheye lens, allowing it to maintain image plane stability without focusing within a temperature range of -20°C to 60°C. It exhibits good confocality in both daytime and nighttime images, meeting current market demands for surveillance lenses. Furthermore, the plastic lenses can be mass-produced using molding, reducing costs. Attached Figure Description

[0022] Figure 1 Composition and light distribution diagram of this compact visible-band wide-angle heat-absorbing lens;

[0023] Figure 2 Lens markings and surface markings of the compact visible-band wide-angle heat-absorbing lens of the present invention;

[0024] Figure 3 The relative illumination curve of the compact visible-band wide-angle heat-absorbing lens of the present invention;

[0025] Figure 4 MTF curve of the compact visible-band wide-angle heat-absorbing lens of the present invention at a temperature of -20 degrees Celsius;

[0026] Figure 5 MTF curve of the compact visible wide-angle heat-absorbing lens of the present invention at a temperature of 20 degrees Celsius;

[0027] Figure 6 MTF curve of the compact visible wide-angle heat-absorbing lens of the present invention at a temperature of 60 degrees Celsius;

[0028] Figure 7 The light spot pattern of the compact visible wide-angle heat-absorbing lens of the present invention at a temperature of -20 degrees Celsius;

[0029] Figure 8 The light spot pattern of the compact visible wide-angle heat-absorbing lens of the present invention at a temperature of 20 degrees Celsius;

[0030] Figure 9 The light spot pattern of the compact visible wide-angle heat-absorbing lens of the present invention at a temperature of 60 degrees Celsius; Detailed Implementation

[0031] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0032] like Figure 1As shown, a compact visible-band wide-angle heat-absorbing lens includes, along the optical path propagation direction, a first lens 1, a second lens 2, an aperture stop P, a third lens 3, a fourth lens 4, and a fifth lens 5 connected in sequence; the first lens 1 is a negative meniscus plastic lens with both surfaces being even-numbered aspherical surfaces; the second lens 2 is a positive meniscus plastic lens with both surfaces being even-numbered aspherical surfaces; the third lens 3 is a positive diopter glass lens with both surfaces being standard spherical surfaces; the fourth lens 4 is a negative diopter plastic lens with both surfaces being even-numbered aspherical surfaces; and the fifth lens 5 is a positive diopter plastic lens with both surfaces being even-numbered aspherical surfaces.

[0033] The first lens 1, the second lens 2, the fourth lens 4 and the fifth lens 5 of the above lens are all made of plastic and have an even number of aspherical surfaces; the third lens 3 is made of glass and has a standard spherical surface, and the aperture P is located on the third lens 3; the optical part weighs only 0.18 grams.

[0034] The input light enters the lens through the first lens 1, passes sequentially through the second lens 2 to the fifth lens 5, reaches the camera window 6 and the camera filter 7, and finally the focused beam enters the image plane 8. The lens mount is made of plastic.

[0035] like Figure 2 As shown, along the incident direction of the light path, the two sides of the first lens 1 are the first incident surface 11 and the first exit surface 12, the two sides of the second lens 2 are the second incident surface 21 and the second exit surface 22, the two sides of the third lens 3 are the third incident surface 31 and the third exit surface 32, the two sides of the fourth lens 4 are the fourth incident surface 41 and the fourth exit surface 42, the two sides of the fifth lens 5 are the fifth incident surface 51 and the fifth exit surface 52, the two sides of the camera window 6 are the camera incident surface 61 and the camera exit surface 62, and the two sides of the camera filter 7 are the filter incident surface 71 and the filter incident and exit surface 72. The parameters of each lens are shown in Table 1.

[0036] The center-to-center spacing between the first and second lenses is 2.2 mm, between the second and third lenses is 0.2 mm, between the third and fourth lenses is 1.8 mm, and between the fourth and fifth lenses is 0.1 mm. The center thickness of the first lens is 0.8 mm, the second lens is 1.6 mm, the third lens is 1.2 mm, the fourth lens is 0.6 mm, and the fifth lens is 1.5 mm.

[0037] The first incident surface is convex with a radius of curvature of 106.478 mm; the first exit surface is concave with a radius of curvature of 1.754 mm; the second incident surface is concave with a radius of curvature of -4.943 mm; the second exit surface is convex with a radius of curvature of -4.468 mm; the third incident surface is convex with a radius of curvature of 7.668 mm; the third exit surface is convex with a radius of curvature of -2.745 mm; the fourth incident surface is concave with a radius of curvature of 23.772 mm; the fourth exit surface is concave with a radius of curvature of 3.296 mm; the fifth incident surface is convex with a radius of curvature of 6.334 mm; the fifth exit surface is convex with a radius of curvature of -3.261 mm.

[0038] The lens has a focal length of 2.4mm, an F-number of 2.5, a field of view of 155°, an overall length of 13.4mm, an overall optical diameter of less than 8mm, an image plane diameter of 6.5mm, and a passive heat dissipation function. It can maintain image quality without focusing within a temperature range of -20 degrees to 60 degrees.

[0039] Table 1. Parameters of each lens element in the lens.

[0040]

[0041] In Table 1, under the "Surface Type" column, lenses 1 through 5 have two surface types: even-numbered aspherical surfaces and standard spherical surfaces. The expressions for even-numbered aspherical surfaces and standard spherical surfaces are:

[0042]

[0043] Where Z(r) is the distance vector from the vertex of the sphere at a height of r along the optical axis, c = 1 / r, r represents the radius of curvature of the lens surface on the optical axis, k is the conic coefficient, and α1 to α8 are the higher-order aspherical coefficients. For a standard sphere, the values ​​of k and α1 to α8 are all 0. The higher-order aspherical coefficients of each lens are shown in Table 2.

[0044] Table 2 shows the aspherical higher-order coefficients of each lens element in the lens (k and α1 are both 0).

[0045]

[0046]

[0047] Figure 3 The relative illumination curve for the aforementioned lens is given by... Figure 3 It can be seen that the lighting design is excellent, maintaining a relative illuminance of ≥0.5 throughout the entire field of view. Figures 4 to 6 The MTF curves for the lens are shown at ambient temperatures of -20°C, +20°C, and +60°C. Figures 4 to 6It can be seen that the optical performance of this system is good and almost unaffected by temperature in a temperature range of at least -20 degrees Celsius to +60 degrees Celsius. Figures 7 to 9 The figures show the light spot distribution of the above lens at ambient temperatures of -20°C, +20°C, and +60°C. These three figures demonstrate that, within a temperature range of at least -20°C to +60°C, the RMS diameter of the light spot in this system is less than 5 micrometers, and its effect from temperature is negligible. Figures 4 to 9 It can be seen that this system achieves heat dissipation in a temperature range of at least -20 degrees Celsius to +60 degrees Celsius and has good optical performance.

Claims

1. A compact visible-band wide-angle heat-absorbing lens, characterized in that: Along the direction of light propagation, it includes a first lens, a second lens, an aperture stop, a third lens, a fourth lens, and a fifth lens connected in sequence; The first lens is a negative meniscus plastic lens with both surfaces being even-numbered aspherical surfaces; the second lens is a positive meniscus plastic lens with both surfaces being even-numbered aspherical surfaces; the third lens is a positive diopter glass lens with both surfaces being standard spherical surfaces; the fourth lens is a negative diopter plastic lens with both surfaces being even-numbered aspherical surfaces; and the fifth lens is a positive diopter plastic lens with both surfaces being even-numbered aspherical surfaces. The center-to-center distance between the first and second lenses is 2.2 ± 0.2 mm, the center-to-center distance between the second and third lenses is 0.2 ± 0.2 mm, the center-to-center distance between the third and fourth lenses is 1.8 ± 0.2 mm, and the center-to-center distance between the fourth and fifth lenses is 0.1 ± 0.2 mm. The center thickness of the first lens is 0.8±0.2mm, the center thickness of the second lens is 1.6±0.2mm, the center thickness of the third lens is 1.2±0.2mm, the center thickness of the fourth lens is 0.6±0.2mm, and the center thickness of the fifth lens is 1.5±0.2mm. Along the direction of light propagation, the two sides of the first lens are the first incident surface and the first exit surface, the two sides of the second lens are the second incident surface and the second exit surface, the two sides of the third lens are the third incident surface and the third exit surface, the two sides of the fourth lens are the fourth incident surface and the fourth exit surface, and the two sides of the fifth lens are the fifth incident surface and the fifth exit surface. The first incident surface is convex with a radius of curvature of 106.478±0.002 mm; the first exit surface is concave with a radius of curvature of 1.754±0.002 mm; the second incident surface is concave with a radius of curvature of -4.943±0.002 mm; the second exit surface is convex with a radius of curvature of -4.468±0.002 mm; the third incident surface is convex with a radius of curvature of 7.668±0.002 mm. The third exit surface is convex with a radius of curvature of -2.745±0.002mm; the fourth incident surface is concave with a radius of curvature of 23.772±0.002mm; the fourth exit surface is concave with a radius of curvature of 3.296±0.002mm; the fifth incident surface is convex with a radius of curvature of 6.334±0.002mm; the fifth exit surface is convex with a radius of curvature of -3.261±0.002mm.

2. The compact visible-band wide-angle heat-absorbing lens as described in claim 1, characterized in that: The first lens is made of T62R_2017 material; the second lens is made of E48R material; the third lens is made of H-FK61 material; the fourth lens is made of EP9000 material; and the fifth lens is made of E48R material.

3. The compact visible-band wide-angle heat-absorbing lens as described in claim 1 or 2, characterized in that: The optical aperture of the first incident surface is 7.6±0.1 mm, and the optical aperture of the first exit surface is 3.4±0.1 mm; the optical aperture of the second incident surface is 3.1±0.1 mm, and the optical aperture of the second exit surface is 2.7±0.1 mm; the optical aperture of the third incident surface is 2.2±0.1 mm, and the optical aperture of the third exit surface is 3.0±0.1 mm; the optical aperture of the fourth incident surface is 4.0±0.1 mm, and the optical aperture of the fourth exit surface is 4.6±0.1 mm; the optical aperture of the fifth incident surface is 4.6±0.1 mm, and the optical aperture of the fifth exit surface is 4.8±0.1 mm.

4. The compact visible-band wide-angle heat-absorbing lens as described in claim 1 or 2, characterized in that: The focal length is 2.4 mm, the F-number is 2.5, and the field of view is 155°.

5. The compact visible-band wide-angle heat-absorbing lens as described in claim 1 or 2, characterized in that: The overall length is less than 13.4 mm, the overall optical diameter is less than 8 mm, and the image quality remains unchanged without focusing within a temperature range of -20 degrees to 60 degrees.

Images