Wide-spectrum high-sensitivity low-illumination lens

Abstract

The application discloses a wide-spectrum high-sensitivity low-illumination lens, which comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a seventh lens in sequence from an object side to an image side along an optical axis; wherein the second lens and the third lens constitute a cemented lens, the second lens is a biconvex lens with positive refractive power, and the third lens is a biconcave lens with negative refractive power; the first lens, the fifth lens and the sixth lens are lenses with positive refractive power; and the fourth lens and the seventh lens are lenses with negative refractive power. The embodiment of the application reduces the size of the lens, increases the aperture, improves the imaging quality, and can be widely applied to the technical field of optical lenses.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to a wide-spectrum, high-sensitivity, low-light lens. Background Technology

[0002] Existing low-light lenses typically have the following drawbacks: large size and heavy weight; small aperture, resulting in less light intake, darker images, and insufficient detail; they can only be used normally in low-light conditions such as at night, and in bright light conditions such as daytime, low-light lenses will cause flare, resulting in unclear images; and they have significant distortion. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a wide-spectrum, high-sensitivity, low-light lens that reduces lens size, increases aperture, and improves image quality.

[0004] In a first aspect, embodiments of the present invention provide a broadband, high-sensitivity, low-illuminance lens, comprising, in sequence along the optical axis from the object side to the image side, a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a seventh lens; wherein the second lens and the third lens constitute a cemented lens, the second lens being a biconvex lens with positive optical power, and the third lens being a biconcave lens with negative optical power; the first lens, the fifth lens, and the sixth lens are lenses with positive optical power; and the fourth lens and the seventh lens are lenses with negative optical power.

[0005] Optionally, the object-side surfaces of the first, fourth, fifth, and sixth lenses are all convex, and the image-side surfaces are all concave; the object-side surface of the seventh lens is all concave, and the image-side surface is all convex.

[0006] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the first lens satisfy the following:

[0007]

[0008] Where f is the focal length of the broadband high-sensitivity low-light lens, and f1 is the focal length of the first lens.

[0009] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the second lens satisfy the following:

[0010]

[0011] Where f is the focal length of the broadband high-sensitivity low-light lens, and f2 is the focal length of the second lens.

[0012] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the third lens satisfy the following:

[0013]

[0014] Where f is the focal length of the broadband high-sensitivity low-light lens, and f3 is the focal length of the third lens.

[0015] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the cemented lens satisfy the following:

[0016]

[0017] Where f is the focal length of the broadband high-sensitivity low-light lens, and f8 is the focal length of the cemented lens.

[0018] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the fourth lens satisfy the following:

[0019]

[0020] Where f is the focal length of the broadband high-sensitivity low-light lens, and f4 is the focal length of the fourth lens.

[0021] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the fifth lens satisfy the following:

[0022]

[0023] Where f is the focal length of the broadband high-sensitivity low-light lens, and f5 is the focal length of the fifth lens.

[0024] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the sixth lens satisfy the following:

[0025]

[0026] Where f is the focal length of the broadband high-sensitivity low-light lens, and f6 is the focal length of the sixth lens.

[0027] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the seventh lens satisfy the following:

[0028]

[0029] Where f is the focal length of the broadband high-sensitivity low-light lens, and f7 is the focal length of the seventh lens.

[0030] The implementation of this invention provides the following beneficial effects: This invention provides a broadband, high-sensitivity low-light lens, which, along the optical axis from the object side to the image side, sequentially includes a first lens, a cemented lens, an aperture stop, a second lens, a third lens, a fourth lens, and a fifth lens; wherein the first, third, and fourth lenses are convex lenses with positive optical power; the cemented lens includes a sixth and a seventh lens; and the second and fifth lenses are convex lenses with negative optical power. In the low-light lens provided by this invention, the first, second, third, fourth, and fifth lenses are all used to correct phase aberration; the cemented lens is used to reduce chromatic aberration; and the aperture stop is used to limit the beam of incident light. This invention reduces the number of lenses, reduces the size and volume of the lens, and achieves a low-light lens with a large aperture, low distortion, and day / night confocal focus. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a broadband, high-sensitivity, low-light lens provided in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the optical path of a broadband, high-sensitivity, low-light lens provided in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of another broadband, high-sensitivity, low-light lens provided in an embodiment of the present invention;

[0034] Figure 4 These are field curvature and distortion curves of a broadband, high-sensitivity, low-light lens provided in an embodiment of the present invention; wherein, Figure 4 (a) is a field curve diagram. Figure 4 (b) is a distortion curve diagram;

[0035] Figure 5 This is a modulation transfer function curve of a broadband, high-sensitivity, low-light lens provided in an embodiment of the present invention. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0037] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0038] In the following description, the terms "first, second, third" are used merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first, second, third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of the invention described herein can be implemented in an order other than that illustrated or described herein.

[0039] Unless otherwise defined, all technical and scientific terms used in the embodiments of this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in the embodiments of this invention is for descriptive purposes only and is not intended to limit the invention.

[0040] Before providing a further detailed description of the embodiments of the present invention, the nouns and terms involved in the embodiments of the present invention will be explained, and the nouns and terms involved in the embodiments of the present invention shall be interpreted as follows.

[0041] like Figure 1 As shown, this embodiment of the invention provides a broadband, high-sensitivity, low-light lens, which includes, along the optical axis from the object side to the image side, a first lens 1, a second lens 2, a third lens 3, an aperture stop 8, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a seventh lens 7. The second lens 2 and the third lens 3 form a cemented lens; the second lens 2 is a biconvex lens with positive optical power, and the third lens 3 is a biconcave lens with negative optical power. The first lens 1, the fifth lens 5, and the sixth lens 6 are lenses with positive optical power; the fourth lens 4 and the seventh lens 7 are lenses with negative optical power.

[0042] Specifically, such as Figure 2 As shown, the low-light lens provided in this embodiment of the invention is used in combination with a camera. The low-light lens provided in this embodiment of the invention may also include a protective sheet 10. Light passes through the second lens 2, the third lens 3, the aperture 8, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7 and the protective sheet 10 in sequence to form an image on the image plane 9.

[0043] Specifically, after passing through the low-light lens provided in this embodiment of the invention, light illuminates the photosensitive chip of the camera to form an image.

[0044] Specifically, the first lens 1 is used for collimation and focusing; the cemented lens is used to eliminate chromatic aberration; the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 are used to correct phase aberration; and the aperture stop 8 is used to limit the beam of incident light.

[0045] Specifically, a protective sheet 10 is provided after the seventh lens 7. The protective sheet 10 is used to protect the photosensitive chip in the camera that uses a wide-spectrum, high-sensitivity, low-light lens, and to prevent external damage to the photosensitive chip.

[0046] Specifically, the light emitted from the seventh lens 7 passes through the protective sheet 10 and illuminates the image plane 9; the image plane 9 includes the surface of the photosensitive chip.

[0047] Specifically, the material of the protective sheet 10 includes glass, and the specific material is determined according to the actual situation. No limitation is made in this embodiment of the invention.

[0048] Specifically, the materials of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, and the seventh lens 7 include optical glass. The specific lens materials are determined according to the actual situation and are not limited in this embodiment of the invention.

[0049] Optionally, the object-side surfaces of the first lens 1, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are all convex, and the image-side surfaces are all concave; the object-side surface of the seventh lens 7 is all concave, and the image-side surface is all convex.

[0050] Specifically, the first lens 1 or the fifth lens 5 is a convex lens; the fourth lens 4 or the sixth lens 6 is a meniscus lens; and the seventh lens 7 is a concave lens.

[0051] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the first lens 1 satisfy the following:

[0052]

[0053] Where f is the focal length of the broadband high-sensitivity low-light lens, and f1 is the focal length of the first lens 1.

[0054] Specifically, the optical power of the first lens 1 ranges from 0.001 to 0.02 mm. -1 The specific optical power range is determined based on actual conditions, and is not limited in the embodiments of this invention. Examples are provided for reference only, such as an optical power of 0.011mm. -1 .

[0055] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the second lens 2 satisfy the following:

[0056]

[0057] Where f is the focal length of the broadband high-sensitivity low-light lens, and f2 is the focal length of the second lens 2.

[0058] Specifically, the optical power of the second lens 2 ranges from 0.01 to 0.02 mm. -1 The specific range of optical power is determined based on actual conditions, and is not limited in the embodiments of this invention. Examples are provided for reference only, such as an optical power of 0.01mm. -1 .

[0059] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the third lens 3 satisfy the following:

[0060]

[0061] Where f is the focal length of the broadband high-sensitivity low-light lens, and f3 is the focal length of the third lens 3.

[0062] Specifically, the optical power range of the third lens 3 is -0.01 to -0.025 mm. -1 The specific optical power range is determined based on actual conditions, and is not limited in the embodiments of this invention. Examples are provided for reference only, such as an optical power of -0.017mm. -1 .

[0063] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the cemented lens satisfy the following:

[0064]

[0065] Where f is the focal length of the broadband high-sensitivity low-light lens, and f8 is the focal length of the cemented lens.

[0066] Specifically, a cemented lens is composed of a biconvex lens with positive optical power and a biconcave lens with negative optical power; the biconvex lens is used to focus the incident light, and the biconcave lens is used to diverge the incident light; the cemented lens eliminates chromatic aberration of the incident light by using a biconvex lens and a biconcave lens with different dispersion properties.

[0067] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the fourth lens 4 satisfy the following:

[0068]

[0069] Where f is the focal length of the broadband high-sensitivity low-light lens, and f4 is the focal length of the fourth lens 4.

[0070] Specifically, the optical power range of the fourth lens 4 is -0.01 to -0.02 mm. -1 The specific optical power range is determined based on actual conditions, and is not limited in the embodiments of this invention. Examples are provided for reference only, such as an optical power of 0.016mm. -1 .

[0071] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the fifth lens 5 satisfy the following:

[0072]

[0073] Where f is the focal length of the broadband high-sensitivity low-light lens, and f5 is the focal length of the fifth lens 5.

[0074] Specifically, the optical power of the fifth lens 5 ranges from 0.03 to 0.04 mm. -1 The specific optical power range is determined based on actual conditions, and is not limited in the embodiments of this invention. Examples are provided for reference only, such as an optical power of 0.037mm. -1 .

[0075] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the sixth lens 6 satisfy the following:

[0076]

[0077] Where f is the focal length of the broadband high-sensitivity low-light lens, and f6 is the focal length of the sixth lens 6.

[0078] Specifically, the optical power of the sixth lens 6 ranges from 0.015 to 0.02 mm. -1 The specific optical power range is determined based on actual conditions, and is not limited in the embodiments of this invention. Examples are provided for reference only, such as an optical power of 0.017mm. -1 .

[0079] Optionally, the focal length of the broadband high-sensitivity low-light lens and the focal length of the seventh lens 7 satisfy the following:

[0080]

[0081] Where f is the focal length of the broadband high-sensitivity low-light lens, and f7 is the focal length of the seventh lens 7.

[0082] Specifically, the optical power range of the seventh lens 7 is -0.04 to -0.05 mm. -1 The specific optical power range is determined based on actual conditions, and is not limited in the embodiments of this invention. Examples are provided for reference only, such as an optical power of -0.046mm. -1 .

[0083] In one specific embodiment, the surface sequence of the low-light lens is as follows: Figure 3 As shown, the broadband high-sensitivity low-light lens includes a protective sheet 10, the two surfaces of which are S14 and S15 respectively; S4 is the cementing surface of the cemented lens; the parameters of the broadband high-sensitivity low-light lens are shown in Table 1.

[0084]

[0085] Table 1

[0086] Specifically, through simulation, the target surface size of the broadband high-sensitivity low-light lens is 1157×871μm, and the diagonal of the target surface is 13μm; the focal length of the broadband high-sensitivity low-light lens is 49.9mm; the focusing range is 5m~∞; the distortion rate is 0.5%; the operating temperature range is -50~70℃; the operating wavelength range is 450~1000nm; and the relative illumination is greater than 45%.

[0087] Specifically, the target surface refers to the plane in an optical system where light is focused to form an image, typically the largest area on the image sensor where light passes through the lens and is imaged.

[0088] Specifically, such as Figure 4 As shown, through simulation, the field curvature and distortion curves of a broadband high-sensitivity low-light lens under incident light wavelengths of 450nm, 486nm, 587nm, 656nm, 800nm, and 1000nm were obtained; among them, Figure 4 (a) and Figure 4 (b) The ordinate represents the field of view angle; field curvature is an aberration in which the object plane forms a curved image, characterized by meridional and sagittal field curvature. Excessive field curvature and distortion severely affect the off-axis ray imaging quality of the optical system; when the lens distortion is less than 4%, it is difficult for the human eye to perceive. Figure 3 It can be seen that, under incident light with a wavelength of 450nm, the maximum field curvature of the broadband high-sensitivity low-light lens is about 0.16mm, and the maximum distortion is 0.57%. Both the field curvature and distortion are very small and almost imperceptible to the human eye.

[0089] Specifically, such as Figure 5 As shown, the horizontal axis represents spatial frequency in line pairs per millimeter (lp / mm), and the vertical axis represents the OTF (Optical Transfer Function). A smoother MTF curve indicates better image quality for a wide-spectrum, high-sensitivity, low-light lens. The figure shows that at the edge of the field of view, with a spatial frequency of 39 lp / mm, the MTF value is 0.36, indicating a relatively smooth MTF curve that meets the requirements for human visual observation.

[0090] The implementation of this invention provides the following beneficial effects: This invention provides a broadband, high-sensitivity, low-light lens, which, along the optical axis from the object side to the image side, sequentially includes a first lens, a cemented lens, an aperture stop, a second lens, a third lens, a fourth lens, and a fifth lens; wherein the first, third, and fourth lenses are convex lenses with positive optical power; the cemented lens includes a sixth and a seventh lens; and the second and fifth lenses are convex lenses with negative optical power. In the low-light lens provided by this invention, the first, second, third, fourth, and fifth lenses are all used to correct phase aberration; the cemented lens is used to reduce chromatic aberration; and the aperture stop is used to limit the incident light beam. The low-light lens of this invention reduces the number of lenses, thus reducing the size and volume of the lens. By sequentially combining the first lens, cemented lens, aperture, second lens, third lens, fourth lens, and fifth lens along the optical axis from the object side to the image side, field curvature and distortion are reduced, and image quality is improved. The working wavelength range is 450–1000 nm, realizing a low-light lens with a large aperture, low distortion, and day and night confocal focus.

[0091] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A broadband, high-sensitivity, low-light lens, characterized in that, Along the optical axis from the object side to the image side, the lens consists of a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a seventh lens. The second and third lenses form a cemented lens. The second lens is a biconvex lens with positive optical power, and the third lens is a biconcave lens with negative optical power. The first, fifth, and sixth lenses are lenses with positive optical power; the fourth and seventh lenses are lenses with negative optical power. The object-side surfaces of the first, fourth, fifth, and sixth lenses are all convex, and the image-side surfaces are all concave. The object-side surface of the seventh lens is all concave, and the image-side surface is all convex.

2. The broadband, high-sensitivity, low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens satisfies the following condition: ， in, The focal length of the broadband, high-sensitivity, low-light lens. Let be the focal length of the first lens.

3. The broadband high-sensitivity low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens and the focal length of the second lens satisfy the following: ， in, The focal length of the broadband, high-sensitivity, low-light lens. is the focal length of the second lens.

4. The broadband high-sensitivity low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens and the focal length of the third lens satisfy the following: ， in, The focal length of the broadband, high-sensitivity, low-light lens. Let be the focal length of the third lens.

5. The broadband high-sensitivity low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens and the focal length of the cemented lens satisfy the following: ， in, The focal length of the broadband, high-sensitivity, low-light lens. Let be the focal length of the cemented lens.

6. The broadband high-sensitivity low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens and the focal length of the fourth lens satisfy the following: ， in, The focal length of the broadband, high-sensitivity, low-light lens. The focal length of the fourth lens is given.

7. The broadband high-sensitivity low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens and the focal length of the fifth lens satisfy the following: ， in, The focal length of the broadband, high-sensitivity, low-light lens. The focal length of the fifth lens is given.

8. The broadband high-sensitivity low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens and the focal length of the sixth lens satisfy the following: ， in, The focal length of the broadband, high-sensitivity, low-light lens. The focal length of the sixth lens is given.

9. The broadband high-sensitivity low-light lens according to claim 1, characterized in that, The focal length of the broadband high-sensitivity low-light lens and the focal length of the seventh lens satisfy the following: ， in, The focal length of the broadband, high-sensitivity, low-light lens. The focal length of the seventh lens is given.

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