Day and night confocal low-light lens and optical system

Abstract

The invention discloses a day and night confocal low-light-level lens and an optical system, the low-light-level lens comprises a front group lens, a diaphragm and a rear group lens from an object space to an image space, the front group lens comprises a first lens with positive focal power, a first bonding lens with negative focal power and a second bonding lens with negative focal power, the first bonding lens comprises a second lens with negative focal power and a third lens with negative focal power, and the second bonding lens comprises a fourth lens with negative focal power and a fifth lens with negative focal power. The rear group lens comprises a sixth lens with positive focal power, a seventh lens with positive focal power, an eighth lens with negative focal power and a ninth lens with positive focal power; the diaphragm is arranged between the front group lens and the rear group lens; by setting the position distribution of different lenses and distributing different focal powers, the focus offset of the low-light-level lens during switching of different working states is reduced, day and night confocal is realized, and the imaging quality is improved. The embodiment of the invention can be widely applied to the technical field of optical elements.

Description

Technical Field

[0001] The present application relates to the technical field of optical elements, and in particular to a day-night confocal low-light level lens and optical system. Background Art

[0002] Existing camera equipment achieves night vision effects by using infrared lenses or low-light-level lenses. However, existing infrared lenses require the installation of additional infrared light sources, or require the imaged object to have a certain temperature in order to achieve night vision effects, and their environmental adaptability is insufficient. Therefore, most of them use low-light-level lenses to achieve night vision effects with the help of visible light and near-infrared light in natural light. However, existing low-light-level lenses are large in size, and focus shifts when switching between visible light and near-infrared working states, affecting imaging quality and night vision effects. Summary of the Invention

[0003] The main purpose of the embodiments of the present application is to provide a low-light-level lens and optical system that is confocal during the day and night, which can achieve confocality during the day and night and improve imaging quality.

[0004] To achieve the above-mentioned purpose, one aspect of an embodiment of the present application provides a day and night confocal low-light level lens, wherein the low-light level lens includes a front lens group, an aperture, and a rear lens group along the direction from the object side to the image side; wherein:

[0005] The front lens group includes a first lens having positive power, a first cemented lens having negative power, and a second cemented lens having negative power; wherein the first cemented lens includes a second lens having negative power and a third lens having negative power, and the second cemented lens includes a fourth lens having positive power and a fifth lens having negative power;

[0006] The rear lens group includes a sixth lens having positive refractive power, a seventh lens having positive refractive power, an eighth lens having negative refractive power, and a ninth lens having positive refractive power.

[0007] In some embodiments, the second lens is made of a high-dispersion material, and the third lens is made of a low-dispersion material;

[0008] Alternatively, the second lens is made of a low-dispersion material, and the third lens is made of a high-dispersion material.

[0009] In some embodiments, the fourth lens is made of a high-dispersion material, and the fifth lens is made of a low-dispersion material;

[0010] Alternatively, the fourth lens is made of a low-dispersion material, and the fifth lens is made of a high-dispersion material.

[0011] In some embodiments, the focal length of the first cemented lens and the focal length of the second cemented lens respectively satisfy the following relationship:

[0012]

[0013] Wherein, f is the total focal length of the low light level lens, f B1 is the focal length of the first doublet lens, f B2 is the focal length of the second cemented lens.

[0014] In some embodiments, the first lens, the third lens, the fifth lens, and the seventh lens include positive meniscus lenses, the sixth lens and the ninth lens include biconcave lenses, the second lens and the eighth lens include convex lenses, and the fourth lens includes a negative meniscus lens.

[0015] In some embodiments, the first to ninth lenses include spherical lenses.

[0016] In some embodiments, the apertures of the first to ninth lenses decrease sequentially from the object side to the image side.

[0017] In some embodiments, the focal lengths of the first lens to the ninth lens respectively satisfy the following relationship:

[0018]

[0019] Among them, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, f8 is the focal length of the eighth lens, f9 is the focal length of the ninth lens, and f is the total focal length of the micro-light lens.

[0020] In some embodiments, the micro-light lens further includes a protective glass; wherein the protective glass is disposed on the image side of the ninth lens and satisfies the following relationship:

[0021] 3.0≤d 9,2 +d 10,1 +d 10,2 ≤8.0

[0022] Among them, d 9,2 is the thickness of the second surface of the ninth lens, d 10,1 is the first surface thickness of the protective glass, d 10,2 is the second surface thickness of the protective glass.

[0023] To achieve the above-mentioned purpose, another aspect of an embodiment of the present application provides a day and night confocal optical system, which includes a photosensitive unit and any of the low-light lenses described above.

[0024] The implementation of the embodiments of the present application includes the following beneficial effects: the embodiments of the present application provide a day and night confocal micro-light lens and an optical system, the micro-light lens including a front group lens, an aperture and a rear group lens along the object side to the image side; the front group lens includes a first lens with optical power, a first cemented lens with negative optical power and a second cemented lens with negative optical power, the first cemented lens includes a second lens with negative optical power and a third lens with negative optical power, the second cemented lens includes a fourth lens with positive optical power and a fifth lens with negative optical power, the rear group lens includes a sixth lens with positive optical power, a seventh lens with positive optical power, an eighth lens with negative optical power and a ninth lens with positive optical power, and the aperture is arranged between the front group lens and the rear group lens; by setting the position of each lens and reasonably allocating the optical power of each lens, the focus offset when switching between different working states is reduced, and day and night confocality is achieved. Through the combination of different lenses, the chromatic aberration and aberration of the incident light are corrected, and the imaging quality is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of a day and night confocal low-light level lens provided in an embodiment of the present application;

[0026] Figure 2 This is a schematic structural diagram of another day-night confocal low-light-level lens provided in an embodiment of the present application;

[0027] Figure 3 This is a schematic diagram of the lens surface sequence of a day-night confocal low-light level lens provided in an embodiment of the present application;

[0028] Figure 4 This is an MTF curve diagram of a day and night confocal low-light-level lens provided in an embodiment of the present application;

[0029] Figure 5 This is a field curvature and distortion curve diagram of a day and night confocal low-light-level lens provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are provided for ease of explanation only and do not limit the order of the steps. The order of execution of the steps in the embodiments can be adaptively adjusted based on the understanding of those skilled in the art.

[0031] In the following description, reference is made to “some embodiments”, which describes a subset of all possible embodiments, but it will be 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.

[0032] In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0033] Unless otherwise defined, all technical and scientific terms used in the embodiments of this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the embodiments of this application are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0034] Before further explaining the embodiments of the present application in detail, the nouns and terms involved in the embodiments of the present application are explained. The nouns and terms involved in the embodiments of the present application are subject to the following interpretations.

[0035] Clearance F number: Aperture size, used to describe the aperture of an optical lens. The smaller the clear F number, the larger the aperture.

[0036] Image plane: The size of the camera sensor, measured diagonally, where one inch of the sensor is 16 mm.

[0037] Optical power: It characterizes the ability of an optical system to deflect light. It is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam, and is expressed as the reciprocal of the image-side focal length.

[0038] Abbe number: An index used to indicate the dispersion ability of a transparent medium. The larger the refractive index of the medium, the more severe the dispersion and the smaller the Abbe number. Conversely, the smaller the refractive index of the medium, the milder the dispersion and the larger the Abbe number.

[0039] Among the related technologies, night vision technology mainly includes two fields: far infrared and low light level. Among them, low light level night vision technology mainly relies on low light level lenses, which use the low light level lenses to observe the imaged objects with the help of visible light and near-infrared light in natural light. However, the lenses and sensors used for far-infrared night vision are relatively expensive, and far-infrared night vision technology requires a temperature difference between the object itself and the surrounding environment. Currently, there is technology to hide itself in the far infrared, so low light level night vision technology is more commonly used. General low light level lenses will experience lens focus shift when switching between visible light and near-infrared light, resulting in reduced image quality and affecting night vision effects. At the same time, in order to allow more light to enter, low light level lenses are usually larger in size and have poor portability.

[0040] In view of this, the embodiments of the present application provide a day and night confocal low-light lens and an optical system. The low-light lens improves the overall optical focal length of the low-light lens by combining and arranging several lenses and assigning different optical focal lengths to different lenses, thereby enhancing the low-light lens's ability to focus light and thus improving the imaging quality of the low-light lens. At the same time, lenses with different dispersion capabilities are combined to obtain several cemented lens combinations, and different optical focal lengths are assigned to different cemented lens combinations. The incident light of the low-light lens is corrected by the combined cemented lenses, thereby reducing the field curvature and distortion of the low-light lens imaging, improving the imaging clarity of the low-light lens, and thus improving the imaging quality. The apertures of several lenses in the low-light lens are selected and arranged in a certain order, so that the low-light lens has an ultra-large aperture, thereby increasing the light transmittance of the low-light lens and thus improving the imaging resolution of the low-light lens.

[0041] Figure 1 FIG. 1 is a structural diagram of a day-night confocal low-light-level lens provided in an embodiment of the present application. Figure 1 As shown, the micro-light lens includes a front lens group T1, an aperture S and a rear lens group T2 along the object side to the image side, wherein:

[0042] The front lens group T1 includes a first lens G1 with positive refractive power, a first cemented lens with negative refractive power, and a second cemented lens with negative refractive power. The first cemented lens includes a second lens G2 with negative refractive power and a third lens G3 with negative refractive power. The second cemented lens includes a fourth lens G4 with positive refractive power and a fifth lens G5 with negative refractive power.

[0043] The aperture S is set between the front lens group T1 and the rear lens group T2 to limit the light aperture;

[0044] The rear lens group T2 includes a sixth lens G6 having positive refractive power, a seventh lens G7 having positive refractive power, an eighth lens G8 having negative refractive power, and a ninth lens G9 having positive refractive power.

[0045] In the embodiment of the present application, the micro-light lens is provided with two lens groups, a front lens group T1 and a rear lens group T2. The front lens group T1 is composed of five lenses, and each lens is provided with a different optical power. In the front lens group T1, a first lens G1 to a fifth lens G5 are provided in sequence from the object side to the image side, and the first lens G1 is set to a positive optical power, the second lens G2 is set to a negative optical power, the third lens G3 is set to a negative optical power, the fourth lens G4 is set to a positive optical power, and the fifth lens G5 is set to a negative optical power. At the same time, In the front lens group T1, the second lens G2 and the third lens G3 are combined into a cemented lens group, and this cemented lens group is set to have negative optical power; the fourth lens G4 and the fifth lens G5 are set to another cemented lens group, and this cemented lens group is set to have negative optical power. In the front lens group T1, the first lens G1 refracts external incident light into the front lens group T1, and then the incident light is processed by the two cemented lens groups in sequence to perform chromatic aberration correction and aberration correction, and then the processed incident light is transmitted to the rear lens group T2.

[0046] The rear lens group T2 consists of four lenses, each with a different optical power. Within the rear lens group T2, lens groups G6 through G9 are sequentially arranged from the object side to the image side. Lens G6 has a positive optical power, lens G7 has a positive optical power, lens G8 has a negative optical power, and lens G9 has a positive optical power. The optical powers of lenses G7 through G9 are greater than those of the lenses in lens group T1. Therefore, lens group T2 provides the primary optical power for the micro-light lens and transmits incident light from lens group T1 to a photosensitive element of the optical system, such as a photosensor, for imaging. Furthermore, a stop S is provided between lens group T1 and rear lens group T2 to limit the aperture of the micro-light lens and the size of the incident light beam entering lens group T2. This, in turn, limits the imaging range on the image side, reduces interference of stray light on the target imaging beam, and improves the imaging quality of the micro-light lens.

[0047] In some embodiments, the cemented lens group provided in the front lens group T1 is used to refract the incident light refracted by the first lens G1 and entering the front lens group T1, so that the incident light converges or diverges, thereby adjusting the chromatic aberration and aberration of the imaging of the micro-light lens; the lenses combined into the cemented lens are assigned different optical focal lengths, and the optical focal length of the cemented lens can be obtained by calculation based on the assigned optical focal lengths. The total optical focal length of the micro-light lens is adjusted by the optical focal length of the cemented lens, thereby adjusting the imaging effect of the micro-light lens.

[0048] In some embodiments, a cemented lens is obtained by combining several different lenses, for example, different lenses are superimposed by glue to obtain a cemented lens; according to the desired optical effect of the cemented lens, lenses of different types, materials or characteristics are selected, and the positions and superposition order of the selected lenses are adjusted to determine the final lens position combination; finally, the final lens position combination is tightly combined using appropriate glue or gluing technology to obtain a cemented lens with the desired optical effect; in this embodiment, the cemented lens plays the role of chromatic aberration correction and aberration correction, so lenses with different dispersion capabilities are used to make the cemented lens, specifically, a lens with high dispersion capability is combined with a lens with low dispersion capability to obtain the cemented lens in this embodiment.

[0049] In some embodiments, the focal lengths of the two cemented lenses in the front lens group T1 satisfy the following conditions:

[0050]

[0051] Wherein, f is the total focal length of the low light level lens, f B1 is the focal length of the first doublet lens, f B2 is the focal length of the second cemented lens. By setting the focal length range of the cemented lens, the light converging ability of the cemented lens is adjusted, the light converging ability of the low-light-level lens is improved, and thus the imaging quality is improved.

[0052] In some embodiments, each lens in the front lens group T1 and the rear lens group T2 is designed as a spherical lens, without aspherical and diffractive surfaces, to reduce the production and processing costs of the micro-light lens; illustratively, the material of each lens in this embodiment is fused quartz with high transparency, and each lens can also be made of colorless optical glass; the embodiment of the application does not impose any specific restrictions on the material of each lens, and it can be determined according to actual application requirements.

[0053] In some embodiments, the first lens G1, the third lens G3, the seventh lens G7, and the ninth lens G9 in the front lens group T1 and the rear lens group T2 are all configured as positive meniscus lenses, the eighth lens G8 is configured as a negative meniscus lens, the second lens G2 and the fifth lens G5 are configured as biconcave lenses, and the fourth lens G4 and the sixth lens G6 are both configured as convex lenses; wherein the object side of the positive meniscus lens is convex, the image side of the positive meniscus lens is concave, and the center of the positive meniscus lens is thicker than the edge, and has a positive focal length, which can reduce the focal length of the other lens and maintain micro focus. Angular resolution of optical lens; the object side of the negative meniscus lens is convex, the image side of the negative meniscus lens is concave, and the center of the negative meniscus lens is thinner than the edge, with a negative focal length, which can expand the incident light beam, increase the focal length and reduce the lens aperture; the double concave lens has two concave surfaces, the center of the lens is thinner than the edge, with a negative focal length, which is used to collimate the incident light beam, adjust the focal length of the optical system or adjust the image size; the convex lens includes at least one convex surface, including a double convex lens and a plano-convex lens, the center of the lens is thicker than the edge, has a positive focal length, can converge the light beam or enlarge the image size.

[0054] In some embodiments, the first lens G1 to the ninth lens G2 in the front lens group T1 and the rear lens group T2 are arranged sequentially from the object side to the image side, and the aperture of each lens is set to decrease sequentially from the object side to the image side, thereby increasing the aperture of the micro-light lens, increasing the amount of light passing through the micro-light lens, and improving the imaging quality of the micro-light lens; illustratively, in the lens combination in this embodiment, the aperture of the first lens G1 is set to 12 mm, and the apertures of the other lenses are sequentially decreased, so that the F number of the micro-light lens is 1.0, with an ultra-large aperture; at the same time, the sequential decrease in the aperture of each lens reduces the volume of the lens combination, thereby reducing the volume of the micro-light lens, improving the convenience of the micro-light lens, and expanding the applicable scenarios of the lens.

[0055] In some embodiments, the focal lengths of the lenses in the micro-light lens satisfy the following conditions:

[0056]

[0057] Among them, f1 is the focal length of the first lens G1, f2 is the focal length of the second lens G2, f3 is the focal length of the third lens G3, f4 is the focal length of the fourth lens G4, f5 is the focal length of the fifth lens G5, f6 is the focal length of the sixth lens G6, f7 is the focal length of the seventh lens G7, f8 is the focal length of the eighth lens G8, f9 is the focal length of the ninth lens G9, and f is the total focal length of the micro-light lens.

[0058] In some embodiments, a protective glass D is disposed behind the ninth lens G9 of the rear lens group T2 of the micro-light lens system. Specifically, the thickness of the second surface of the ninth lens G9 is shortened, and a transparent protective glass D is disposed between the second surface of the ninth lens G9 and the sensor that receives incident light. This reduces interference of the protective glass with the light beams transmitted by the lenses in the front lens group T1 and the rear lens group T2. At the same time, the protective glass D is used to protect precision components such as sensors in the optical system.

[0059] In some embodiments, the thickness of the protective glass D disposed behind the rear lens group T2 satisfies the following conditions:

[0060] 3.0≤d1+d2+d3≤8.0

[0061] Wherein, d1 is the thickness of the second surface of the ninth lens element G9, d2 is the thickness of the first surface of the protective glass D, and d3 is the thickness of the second surface of the protective glass D. Exemplarily, both the first and second surfaces of the protective glass D are configured as planes to reduce interference of the protective glass D with the incident light beam. If the protective glass D is not provided behind the rear lens group T2, the thickness of the second surface of the ninth lens element G9 in the rear lens group T2 is appropriately increased. Exemplarily, in this embodiment, when the protective glass D is not provided behind the rear lens group T2, the thickness of the second surface of the ninth lens element G9 in the rear lens group T2 satisfies the following condition:

[0062] 3.0≤d1≤8.0

[0063] Wherein, d1 is the second surface thickness of the ninth lens G9.

[0064] The following describes the solution provided by this application in detail with reference to specific application examples.

[0065] like Figure 2 As shown, Figure 2 The present invention is a schematic structural diagram of a day and night confocal micro-light lens, which includes nine lenses arranged along the incident light. From the object side to the image side, the first lens G1 is a positive meniscus lens with positive focal power, the second lens G2 is a biconcave lens with negative focal power, the third lens G3 is a positive meniscus lens with negative focal power, the fourth lens G4 is a convex lens with positive focal power, the fifth lens G5 is a biconcave lens with negative focal power, the sixth lens G6 is a convex lens with positive focal power, the seventh lens G7 is a positive meniscus lens with positive focal power, the eighth lens G8 is a negative meniscus lens with negative focal power, and the ninth lens G9 is a positive meniscus lens with positive focal power. Figure 2It can be seen that the second lens G2 of the biconcave lens and the third lens G3 of the positive meniscus lens are closely combined to form a first group of cemented lenses, and the fourth lens G4 of the convex lens and the fifth lens G5 of the biconcave lens are closely combined to form a second group of cemented lenses. The incident light beam refracted by the first lens G1 is refracted and diffracted multiple times by the first and second groups of cemented lenses to correct the chromatic aberration and aberration of the incident light beam; an aperture S is set between the fifth lens G5 and the sixth lens G6, and the aperture S divides the several lenses into two groups, and the first lens G1 to the fifth lens G Lens 5 represents the front lens group T1, and lenses G6 through G9 form the rear lens group T2. An incident light beam is refracted by lens G1 and enters the lens group. It then passes through the first and second cemented lens groups, undergoing multiple refractions and diffractions to correct chromatic aberrations and image aberrations. The incident light beam is filtered by an aperture, allowing the primary imaging beam to pass through, reducing interference from stray light or background light. Furthermore, a transparent protective glass D is placed between lens G9 and the image plane to protect the delicate area behind the lens group and reduce interference with the incident light beam.

[0066] In this embodiment, the aperture parameters of each lens in the low-light lens are as follows:

[0067] Table 1

[0068] Lens serial number Lens diameter (mm) G1 12 G2 10 G3 9 G4 8.7 G5 8.7 G6 9.3 G7 8 G8 6.3 G9 5

[0069] According to the above table, the aperture of each lens decreases in sequence from the first lens G1 to the ninth lens G9, and the aperture of the first lens G1 is the largest, which is 12 mm. In this embodiment, the maximum aperture of the lenses in the lens group of the micro-light lens does not exceed 15 mm, so that the micro-light lens has an ultra-large aperture and an F number of 1.0, which increases the light throughput of the micro-light lens and thus improves the resolution of the lens imaging. By setting the distribution position of each lens and adopting an athermal design, the operating temperature range of the lens group is widened, and the applicability of the micro-light lens is improved, thereby obtaining a micro-light lens; the focal length of the micro-light lens is 22 mm, the light throughput F number is 1.0, and the micro-light lens has a focal length of 22 mm. The field of view of the optical lens is 22.32° (D) × 19.08° (H) × 11.7° (V), where D represents the diagonal direction of the sensor, H represents the horizontal direction of the sensor, and V represents the vertical direction of the sensor. The sensor size applicable to the low-light lens is 1960×1200@3.75μm, the applicable wavelength range of the low-light lens is 450nm to 900nm, the total optical length of the low-light lens is 48.05 mm, the relative illumination of the low-light lens is greater than or equal to 50%, the optical distortion of the low-light lens is less than |-0.77%|, and the operating temperature of the low-light lens is -30℃ to 50℃.

[0070] Figure 3 This is a schematic diagram of the surface sequence of several lens surfaces in a low-light lens. Figure 3The thickness, refractive index, Abbe number, and curvature radius of several lens surfaces in the image satisfy the following table, where the thickness of the lens surface is expressed as the distance from the current surface to the next surface of the lens.

[0071] Table 2

[0072]

[0073] Table 2 continued

[0074]

[0075] In Table 2, S1 is the first surface of the first lens G1, S2 is the second surface of the first lens G1, S3 is the first surface of the second lens G2, S4 is the bonding surface between the second surface of the second lens G2 and the first surface of the third lens G3, S5 is the second surface of the third lens G3, S6 is the first surface of the fourth lens G4, S7 is the bonding surface between the second surface of the fourth lens G4 and the first surface of the fifth lens G5, S8 is the second surface of the fifth lens G5, S10 is the first surface of the sixth lens G6, S11 is the second surface of the sixth lens G6, S12 is the first surface of the seventh lens G7, S13 is the second surface of the seventh lens G7, S14 is the first surface of the eighth lens G8, S15 is the second surface of the eighth lens G8, S16 is the first surface of the ninth lens G9, and S17 is the second surface of the ninth lens G9. S18 and S19 are two planes of the cover glass. If the cover glass is not provided in the micro-light lens, the surface thickness range of the second surface of the ninth lens is set to [3.0, 8.0].

[0076] Through the simulation experiment of low-light lens, we can get Figure 4 , Figure 4 This is a Modulation Transfer Function (MTF) curve of the low-light-level lens of this embodiment. The MTF curve can reflect the imaging quality of the low-light-level lens. The smoother the MTF curve transition and the higher the corresponding MTF value, the clearer and sharper the imaging quality of the optical lens or optical system corresponding to the MTF curve. The horizontal axis of the curve is the spatial frequency, whose unit is logarithm per millimeter (lp / mm), and the vertical axis of the curve is the MTF value. According to Figure 4It can be seen that the MLF lens provided in this embodiment has an MTF value of 0.66 in the central field of view at a spatial frequency of 133 lp / mm in the wavelength range of 456 nm to 850 nm, while the MTF value in the edge field of view reaches 0.24, indicating that the MLF lens provided in this embodiment can produce sharp and clear images in the wavelength range of 456 nm to 850 nm. The wavelength range of visible light is 380 nm to 750 nm, and the wavelength range of near-infrared light is 780 nm to 2526 nm. It can be seen that the MLF lens of this embodiment can work under visible light and near-infrared light simultaneously to achieve day and night confocality. The MLF lens of this embodiment can be applied to high-resolution sensors with a single pixel size greater than 3.5 microns.

[0077] Figure 5 (a) is a field curvature curve diagram of the micro-light lens of this embodiment when it is exposed to light of four different wavelengths. Figure 5 (b) is a graph showing the distortion rate of the micro-light lens of this embodiment for four different wavelengths of light. The ordinates of the field curvature and distortion rate graphs represent the field of view angle. Specifically, field curvature is an aberration that forms a curved image on the object plane, characterized by meridional and sagittal field curvatures. Excessive field curvature and distortion of the micro-light lens can seriously affect the imaging quality of off-axis light. The four different wavelengths of light are 486nm, 587nm, 656nm, and 850nm. According to Figure 5 (a) with Figure 5 (b) It can be seen that the field curvature of the low-light-level lens of this embodiment is within 0.03, and the distortion rate is within 1%, indicating that the low-light-level lens of this embodiment has high imaging quality and small imaging distortion under visible light and near-infrared light.

[0078] The implementation of the embodiments of the present application includes the following beneficial effects: The embodiments of the present application provide a day and night confocal micro-light lens and optical system, the micro-light lens including a front lens group, an aperture and a rear lens group along the object side to the image side; wherein the front lens group includes a first lens with positive focal power, a first cemented lens with negative focal power and a second cemented lens with negative focal power, the first cemented lens includes a second lens with negative focal power and a third lens with negative focal power, the second cemented lens includes a fourth lens with positive focal power and a fifth lens with negative focal power, the aperture is arranged between the front lens group and the rear lens group, and the rear lens group includes a sixth lens with positive focal power, a seventh lens with positive focal power, an eighth lens with negative focal power and a ninth lens with positive focal power. By setting the position distribution of each lens and assigning different focal powers to each lens, the focus offset of the lens when switching between different working states is reduced, and day and night confocality is achieved; by setting the position distribution of the lenses, the incident light beam is adjusted in combination with the cemented lens and the aperture, and the imaging quality of the micro-light lens is improved.

[0079] An embodiment of the present application also provides a day and night confocal optical system, including a photosensitive unit and any of the low-light lenses mentioned in the previous embodiments.

[0080] It can be seen that the contents of the above method embodiments are all applicable to the present system embodiments. The functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0081] Embodiments of the present application provide a day-night confocal micro-light lens and optical system. The micro-light lens includes a front lens group, an aperture, and a rear lens group along the object-to-image direction. The front lens group includes a first lens having optical power, a first cemented lens having negative optical power, and a second cemented lens having negative optical power. The first cemented lens includes a second lens having negative optical power and a third lens having negative optical power. The second cemented lens includes a fourth lens having positive optical power and a fifth lens having negative optical power. The rear lens group includes a sixth lens having positive optical power, a seventh lens having positive optical power, an eighth lens having negative optical power, and a ninth lens having positive optical power. The aperture is disposed between the front lens group and the rear lens group. By arranging the position distribution of different lenses and assigning different optical powers to different lenses, focus shift of the micro-light lens when switching between different working states is reduced, thereby achieving day-night confocality. By combining different lenses, incident light is refracted and processed to correct chromatic aberration and aberration, thereby improving the imaging quality of the micro-light lens.

[0082] The above is a specific description of the preferred implementation of the present application, but the invention of the present application is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A day and night confocal low-light level lens, characterized by: The micro-light lens includes a front lens group, an aperture, and a rear lens group along the direction from the object side to the image side; wherein, The front lens group includes a first lens having positive power, a first cemented lens having negative power, and a second cemented lens having negative power; wherein the first cemented lens includes a second lens having negative power and a third lens having negative power, and the second cemented lens includes a fourth lens having positive power and a fifth lens having negative power; The rear lens group includes a sixth lens having positive refractive power, a seventh lens having positive refractive power, an eighth lens having negative refractive power, and a ninth lens having positive refractive power.

2. The low-light lens according to claim 1, characterized in that: The second lens is made of a high-dispersion material, and the third lens is made of a low-dispersion material; Alternatively, the second lens is made of a low-dispersion material, and the third lens is made of a high-dispersion material.

3. The low-light lens according to claim 1, characterized in that: The fourth lens is made of a high-dispersion material, and the fifth lens is made of a low-dispersion material; Alternatively, the fourth lens is made of a low-dispersion material, and the fifth lens is made of a high-dispersion material.

4. The low-light lens according to claim 1, wherein: The focal length of the first cemented lens and the focal length of the second cemented lens respectively satisfy the following relationship: Wherein, f is the total focal length of the low light level lens, f B1 is the focal length of the first doublet lens, f B2 is the focal length of the second cemented lens.

5. The low-light lens according to claim 1, characterized in that: The first lens, the third lens, the fifth lens, and the seventh lens include positive meniscus lenses, the sixth lens and the ninth lens include biconcave lenses, the second lens and the eighth lens include convex lenses, and the fourth lens includes a negative meniscus lens.

6. The low-light lens according to claim 1, characterized in that: The first to ninth lenses include spherical lenses.

7. The low-light lens according to claim 1, wherein: The apertures of the first lens to the ninth lens decrease sequentially from the object side to the image side.

8. The low-light lens according to claim 1, wherein: The focal lengths of the first lens to the ninth lens respectively satisfy the following relationship: Among them, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, f8 is the focal length of the eighth lens, f9 is the focal length of the ninth lens, and f is the total focal length of the micro-light lens.

9. The low-light lens according to claim 1, wherein: The micro-light lens further includes a protective glass; wherein the protective glass is disposed on the image side of the ninth lens and satisfies the following relationship: 3.0≤d 9,2 +d 10,1 +d 10,2 ≤8.0 Among them, d 9,2 is the thickness of the second surface of the ninth lens, d 10,1 is the first surface thickness of the protective glass, d 10,2 is the second surface thickness of the protective glass.

10. A day and night confocal optical system, characterized in that: The optical system includes a photosensitive unit and the low-light lens according to any one of claims 1 to 9.

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