Receiving lens

Abstract

The invention provides a receiving lens, and belongs to the technical field of optical imaging, and the receiving lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged in the optical axis direction, and the object side surfaces and the image side surfaces of the first lens and the fifth lens are rotationally symmetrical aspheric surfaces. The focal powers of the five groups of lenses are negative focal power, positive focal power, negative focal power, positive focal power and positive focal power in sequence along the arrangement direction, or the object side surfaces and the image side surfaces of the first lens and the third lens are rotationally symmetrical aspheric surfaces; the focal powers of the five groups of lenses are negative focal power, negative focal power, positive focal power, positive focal power and positive focal power in sequence along the arrangement direction; wherein the base materials of the five groups of lenses are all high-temperature-resistant materials, and the receiving lens also meets set optical parameter conditions. The receiving lens can meet the requirements of large aperture, small size and high resolution capability under the condition of ensuring that the receiving lens meets a large field angle.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging, and in particular to a receiving lens. Background Art

[0002] In recent years, with the expansion of the photosensitive area and improved low-light performance of CMOS (Complementary Metal Oxide Semiconductor) image sensors, coupled with breakthroughs in DSP (Digital Signal Processing) technology, the application of optical imaging systems in areas such as automotive ADAS (Advanced Driving Assistant Systems), intelligent security, and machine vision has shown a trend of miniaturization and high performance. Ensuring that the receiving lens maintains a large aperture, compact size, and high resolution while maintaining a wide field of view has become a current research focus.

[0003] In the design of existing receiving lenses, for example, patent document CN112099193A discloses a small TOF (Time of Flight) lens, which adopts a hybrid structure including two plastic aspheric lenses and four glass spherical lenses. The TOF lens has a large total optical length and insufficient space utilization. Moreover, due to the use of plastic aspheric lenses, a large amount of defocus will be generated in a high temperature environment, resulting in poor resolution. For example, patent document CN113311571A discloses a small-volume vehicle-mounted TOF lens, which achieves a total optical length of 10 mm through five all-glass lenses and has low distortion. However, its architecture is limited by the Petzval field curvature correction condition, forcing its half field angle to be less than 10 degrees.

[0004] The above technical bottlenecks have led to the contradictions of "large field of view and small size cannot be achieved at the same time" and "high resolution and weather resistance restrict each other" in the actual application field of existing receiving lenses, which has seriously restricted the application and development of receiving lenses. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a receiving lens, aiming to ensure that the receiving lens meets the requirements of large aperture, small size and high resolution while meeting a large field of view.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A receiving lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence along the optical axis direction. The object side and the image side of the first lens are both rotationally symmetric aspherical surfaces, and the object side and the image side of the fifth lens are both rotationally symmetric aspherical surfaces. The optical powers of the five groups of lenses are sequentially negative optical power, positive optical power, negative optical power, positive optical power, and positive optical power along the arrangement direction, or the object side and the image side of the first lens are both rotationally symmetric aspherical surfaces, and the object side and the image side of the third lens are both rotationally symmetric aspherical surfaces. The optical powers of the five groups of lenses are sequentially negative optical power, negative optical power, positive optical power, positive optical power, and positive optical power along the arrangement direction; wherein the base materials of the five groups of lenses are all high-temperature resistant materials; the receiving lens also satisfies the following optical parameter conditions:

[0007] 0.3 < |f1 / f2| < 1.6;

[0008] 0.3 < |f2 / f3| < 2.5;

[0009] 0.2 < |f3 / f4| < 2.55;

[0010] 0.4 < |f4 / f5| < 1.8;

[0011] 20 ≤ TTL ≤ 25.5;

[0012] 90° < FOV < 120°;

[0013] Wherein, f1, f2, f3, f4, and f5 are the effective focal lengths of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens respectively, TTL is the overall optical length of the receiving lens, with the unit of millimeter, and FOV is the field of view angle of the receiving lens.

[0014] In addition, according to the above receiving lens of the present invention, the following additional technical features may also be provided:

[0015] Furthermore, the receiving lens further includes an aperture stop; wherein, when the object side and the image side of the first lens are both rotationally symmetric aspherical surfaces, and the object side and the image side of the fifth lens are both rotationally symmetric aspherical surfaces, the aperture stop is disposed between the first lens and the second lens; when the object side and the image side of the first lens are both rotationally symmetric aspherical surfaces, and the object side and the image side of the third lens are both rotationally symmetric aspherical surfaces, the aperture stop is disposed between the second lens and the third lens.

[0016] Furthermore, the receiving lens satisfies the following optical parameter conditions:

[0017] 0.45 < SL / TTL < 0.85;

[0018] Wherein, SL is the distance from the aperture stop to the image plane of the receiving lens, with the unit of millimeter.

[0019] Further, the receiving lens satisfies the following optical parameter conditions:

[0020] 0.125 < BFL / TTL < 0.195;

[0021] Wherein, BFL is the distance on the optical axis from the image side of the fifth lens to the image plane of the receiving lens, with the unit of millimeter.

[0022] Further, the receiving lens satisfies the following optical parameter conditions:

[0023] 13.5° ≤ θ ≤ 15°;

[0024] Wherein, θ is the maximum principal ray incident angle of the image plane of the receiving lens.

[0025] Further, the receiving lens satisfies the following optical parameter conditions:

[0026] 2.1 ≤ f ≤ 3.5;

[0027] Wherein, f is the total effective focal length of the receiving lens, with the unit of millimeter.

[0028] Further, the receiving lens satisfies the following optical parameter conditions:

[0029] 9 ≤ TTL / IH ≤ 13;

[0030] Wherein, IH is the semi-image height of the target surface of the receiving lens, with the unit of millimeter.

[0031] Further, the receiving lens satisfies the following optical parameter conditions:

[0032] 9 ≤ SD1 ≤ 10;

[0033] 4 ≤ SD5 ≤ 10;

[0034] Wherein, SD1 is the physical aperture of the first lens, and SD5 is the physical aperture of the fifth lens, with the unit of millimeter.

[0035] Further, the receiving lens satisfies the following optical parameter conditions:

[0036] 1.15 ≤ Fno ≤ 1.23;

[0037] Wherein, Fno is the aperture size of the receiving lens.

[0038] Furthermore, the working wavelength band of the receiving lens is 905 nm to 950 nm, and the main wavelength is 940 nm.

[0039] The beneficial effects of the present invention at least include:

[0040] 1. Through the precise optical power distribution of five lenses (two architectures of negative-positive-negative-positive-positive or negative-negative-positive-positive-positive), combined with a specific aspherical layout (aspherical surface of the first / fifth lens or aspherical surface of the first / third lens), and through optical path optimization, a field of view angle of 90 degrees to 120 degrees can be achieved with a relatively short overall optical length, solving the dual requirements of wide-angle imaging and device miniaturization in fields such as vehicle-mounted; 2. All five groups of lenses adopt high-temperature-resistant materials, combined with the design of controlling the aspherical tolerance sensitivity. Compared with the solution containing plastic lenses, the thermal stability is improved, the defocus amount of the lens is low in a high-temperature working environment, and at the same time, through the constraint of the focal length ratio of the lens, the field curvature and spherical aberration can be effectively balanced, meeting the precise ranging requirements of the intelligent driving system under high-temperature working conditions; 3. By controlling the ratio relationship between SL and BFL, while shortening the back focal length, the flatness of the imaging surface can be ensured. At the same time, combined with the reasonable design of the main ray incident angle of the maximum image plane, the illuminance uniformity of the image plane can be improved, and the edge response sensitivity of the image sensor can be enhanced; in addition, the design of a large aperture can also improve the relative illuminance, support clear imaging in low-light environments, and expand the applicable scenarios of the lens. Description of the Drawings

[0041] Figure 1 It is a schematic structural diagram of the receiving lens in Embodiment 1 of the present invention;

[0042] Figure 2 It is an MTF curve diagram of the receiving lens in Embodiment 1 of the present invention;

[0043] Figure 3 It is a field curvature diagram and distortion diagram of the receiving lens in Embodiment 1 of the present invention;

[0044] Figure 4 It is a SPOT SIZE diagram of the receiving lens in Embodiment 1 of the present invention;

[0045] Figure 5 It is a schematic structural diagram of the receiving lens in Embodiment 2 of the present invention;

[0046] Figure 6 It is an MTF curve diagram of the receiving lens in Embodiment 2 of the present invention;

[0047] Figure 7 It is a field curvature diagram and distortion diagram of the receiving lens in Embodiment 2 of the present invention;

[0048] Figure 8 It is a SPOT SIZE diagram of the receiving lens in Embodiment 2 of the present invention;

[0049] Figure 9 It is a schematic structural diagram of the receiving lens in Embodiment 3 of the present invention;

[0050] Figure 10 It is an MTF curve graph of the receiving lens in Embodiment 3 of the present invention;

[0051] Figure 11 It is the field curvature graph and distortion graph of the receiving lens in Embodiment 3 of the present invention;

[0052] Figure 12 It is the SPOT SIZE graph of the receiving lens in Embodiment 3 of the present invention;

[0053] Figure 13 It is a schematic structural diagram of the receiving lens in Embodiment 4 of the present invention;

[0054] Figure 14 It is an MTF curve graph of the receiving lens in Embodiment 4 of the present invention;

[0055] Figure 15 It is the field curvature graph and distortion graph of the receiving lens in Embodiment 4 of the present invention;

[0056] Figure 16 It is the SPOT SIZE graph of the receiving lens in Embodiment 4 of the present invention;

[0057] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0058] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0059] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0060] In the drawings of the present application, for the convenience of illustration, the thickness, size, and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0061] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object being photographed is called the object side of the lens, and the surface of each lens closest to the imaging surface is called the image side of the lens.

[0062] It should also be understood that the terms "comprises", "comprising", "has", "including" and / or "containing" as used herein, when used in this specification, denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. Further, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than individual elements in the list. Further, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplarily" is intended to refer to an example or illustration.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0064] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0065] The features, principles and other aspects of the present application will be described in detail below.

[0066] Please refer to Figure 1 、 Figure 5 、 Figure 9 、 Figure 13, a receiving lens provided by the present invention, includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged in sequence along the optical axis direction. Both the object side and the image side of the first lens L1 are rotationally symmetric aspheres, and both the object side and the image side of the fifth lens L5 are rotationally symmetric aspheres. The optical powers of the five groups of lenses are negative optical power, positive optical power, negative optical power, positive optical power, and positive optical power in sequence along the arrangement direction; or both the object side and the image side of the first lens L1 are rotationally symmetric aspheres, and both the object side and the image side of the third lens L3 are rotationally symmetric aspheres. The optical powers of the five groups of lenses are negative optical power, negative optical power, positive optical power, positive optical power, and positive optical power in sequence along the arrangement direction; wherein, the base materials of the five groups of lenses are all high-temperature resistant materials, so as to ensure good high-temperature resistance performance.

[0067] In addition, the receiving lens provided by the present application also satisfies the following optical parameter conditions:

[0068] 0.3 < |f1 / f2| < 1.6;

[0069] 0.3 < |f2 / f3| < 2.5;

[0070] 0.2 < |f3 / f4| < 2.55;

[0071] 0.4 < |f4 / f5| < 1.8;

[0072] 20 ≤ TTL ≤ 25.5;

[0073] 90° < FOV < 120°;

[0074] Wherein, f1, f2, f3, f4, and f5 are the effective focal lengths of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 respectively. TTL is the overall optical length of the receiving lens, with the unit of millimeter, and FOV is the field of view angle of the receiving lens.

[0075] When the receiving lens provided by the present application satisfies the above conditional expressions, the receiving lens has a good imaging effect and small distortion. And through the reasonable setting of the focal length and optical power, the overall light trend can be adjusted, and the apertures of the head and tail of the lens can be expanded as much as possible, which helps to meet the requirements of high resolution and high depth of field under the condition of a large aperture; in addition, by reasonably distributing the optical power, the overall length of the lens can be controlled within a small range, which can achieve the compactness of the lens, leaving a larger design space for the opto-mechanical structure, greatly compressing the lens size, and laying a foundation for the miniaturization, portability, and lightweight of the product.

[0076] In order to achieve the balance between high imaging quality and compact structure, preferably, the receiving lens provided by the present application also satisfies the optical parameter conditions shown in Table 1:

[0077] Table 1

[0078] <![CDATA[n d1 > <![CDATA[n d2 > <![CDATA[n d3 > <![CDATA[n d4 > <![CDATA[n d5 > 1.69±5％ 1.59±10％ 1.70±15％ 1.75±15％ 1.70±15％ <![CDATA[v d1 > <![CDATA[v d2 > <![CDATA[v d3 > <![CDATA[v d4 > <![CDATA[v d5 > 53.2±5％ 58±45％ 53±60％ 47±10％ 37±25％

[0079] wherein, n d1 、n d2 、n d3 、n d4 、n d5 are the refractive indices of the first lens L1 to the fifth lens L5 in sequence, and v d1 、v d2 、v d3 、v d4 、v d5 are the Abbe numbers of the first lens L1 to the fifth lens L5 in sequence.

[0080] In some alternative embodiments, the receiving lens further includes an aperture stop STO. Specifically, when both the object side and the image side of the first lens L1 are rotationally symmetric aspherical surfaces, and both the object side and the image side of the fifth lens L5 are rotationally symmetric aspherical surfaces, the aperture stop STO is disposed between the first lens L1 and the second lens L5; when both the object side and the image side of the first lens L1 are rotationally symmetric aspherical surfaces, and both the object side and the image side of the third lens L3 are rotationally symmetric aspherical surfaces, the aperture stop STO is disposed between the second lens L2 and the third lens L3.

[0081] In some alternative embodiments, the receiving lens further satisfies the following optical parameter conditions:

[0082] 0.45 < SL / TTL < 0.85;

[0083] wherein, SL is the distance from the aperture stop STO to the image plane of the receiving lens, and the unit is millimeter.

[0084] When the receiving lens provided by the present application satisfies the above conditional formula, the receiving lens has good compactness, aberration correction ability and mechanical adaptability.

[0085] In some alternative embodiments, the receiving lens further satisfies the following optical parameter conditions:

[0086] 0.125 < BFL / TTL < 0.195;

[0087] wherein, BFL is the distance from the image side of the fifth lens to the image plane of the receiving lens on the optical axis, and the unit is millimeter.

[0088] When the receiving lens provided by the present application satisfies the above conditional formula, in combination with the aperture stop position, a balance can be found between the TTL minimization and the BFL functional requirements, so as to balance coma and distortion and achieve the unity of imaging high performance and manufacturability.

[0089] In some alternative embodiments, the receiving lens further satisfies the following optical parameter conditions:

[0090] 13.5° ≤ θ ≤ 15°;

[0091] where θ is the maximum principal ray incident angle on the image plane of the receiving lens.

[0092] When the receiving lens provided in this application satisfies the above conditional formula, the lens has relatively small astigmatism, field curvature, and distortion.

[0093] In some alternative embodiments, the receiving lens further satisfies the following optical parameter conditions:

[0094] 2.1 ≤ f ≤ 3.5;

[0095] where f is the total effective focal length of the receiving lens, with the unit of millimeter.

[0096] In some alternative embodiments, the receiving lens satisfies the following optical parameter conditions:

[0097] 9 ≤ TTL / IH ≤ 13;

[0098] where IH is the semi-image height of the target plane of the receiving lens, with the unit of millimeter.

[0099] When the receiving lens provided in this application satisfies the above conditional formula, the system compactness and the field of view coverage size can be balanced, ensuring a large field of view while miniaturizing the lens.

[0100] In some alternative embodiments, the receiving lens satisfies the following optical parameter conditions:

[0101] 9 ≤ SD1 ≤ 10;

[0102] 4 ≤ SD5 ≤ 10;

[0103] where SD1 is the physical aperture of the first lens L1, and SD5 is the physical aperture of the fifth lens L5, with the unit of millimeter.

[0104] When the receiving lens provided in this application satisfies the above conditional formula, the relatively large apertures at the head and tail of the lens help to meet the requirements of high resolution and high depth of field while ensuring a large aperture.

[0105] In some alternative embodiments, the receiving lens satisfies the following optical parameter conditions:

[0106] 1.15 ≤ Fno ≤ 1.23;

[0107] where Fno is the aperture size of the receiving lens.

[0108] When the receiving lens provided by this application meets the above conditional formula, it can still achieve clear imaging in low-light and dim-light environments, and there is a significant improvement in the detection effect at night in the field of security monitoring. In the field of lidar, detection at a farther distance can also be achieved.

[0109] In some alternative embodiments, the operating wavelength band of the receiving lens is 905 nm to 950 nm, and the main wavelength is 940 nm.

[0110] The following will be combined with Figures 1 to 16 Some specific but non-limiting examples of the embodiments of this application will be described in more detail. It should be noted that the following embodiments mainly analyze the light with a reference wavelength of 940 nm.

[0111] Embodiment 1:

[0112] As Figure 1 shown, a receiving lens provided by the present invention is shown. In this embodiment, the receiving lens includes a first lens L1 with a negative optical power, an aperture stop STO, a second lens L2 with a positive optical power, a third lens L3 with a negative optical power, a fourth lens L4 with a positive optical power, a fifth lens L5 with a positive optical power, and a filter IR, which are arranged in sequence along the optical axis direction, and the lens imaging is on the image plane IMG.

[0113] In terms of shape and structure, the first lens L1 is a meniscus aspherical lens, the second lens L2 is a spherical lens with convex surfaces on both the object side and the image side, the third lens L3 is a spherical lens with a concave object side and a convex image side, the fourth lens L4 is a spherical lens with convex surfaces on both the object side and the image side, and the fifth lens L5 is an aspherical lens with a convex object side and a concave image side; among them, both the object side and the image side of the first lens L1 are rotationally symmetric aspheres, and both the object side and the image side of the fifth lens L5 are rotationally symmetric aspheres.

[0114] In terms of physical dimensions, the physical semi-apertures of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are 4.74 mm, 2.75 mm, 2.77 mm, 2.81 mm, and 2.21 mm respectively. The physical apertures of the five groups of lenses generally show a decreasing trend along the optical axis direction, which can achieve the miniaturized design of the lens.

[0115] In terms of optical parameters, the total effective focal length f of the lens is 2.39 mm, the entrance pupil diameter is 1.96 mm, the true semi-image height IH corresponding to the maximum field of view angle is 2.31 mm, and the ratio of the optical total length TTL to the true semi-image height IH corresponding to the maximum field of view angle is 9.52.

[0116] Specifically, the specific parameters of each lens in the receiving lens in this embodiment and the base material used are shown in Table 2:

[0117] Table 2

[0118]

[0119]

[0120] In Table 2, the base material of each lens is selected as a glass material with high temperature resistance, so that the lens can be applied to high-temperature environments, such as in-vehicle environments. At the same time, considering that the first lens L1 may be exposed to the air, a lens made of D-LAK6 material with high hardness and low abrasion is selected. In addition, the assembly eccentricity of the fifth lens L5 is more sensitive to the performance. Therefore, a single-head installation is adopted in the design, so that its assembly eccentricity and tilt amount can be better controlled during the manufacturing process, thereby reducing the requirements for the manufacturing process and improving the production yield, achieving the purpose of cost reduction.

[0121] In this embodiment, the aspheres of the aspherical lenses (the first lens L1 and the fifth lens L5) satisfy the following aspherical formula:

[0122]

[0123] where Z is the sag height, c is the reciprocal of the radius of curvature R, y is the radial coordinate, k is the conic coefficient, and A2, A3, A4, A5, A6, A7, A8 are the aspherical high-order coefficients. The specific aspherical parameters of the first lens L1 and the fifth lens L5 are shown in Table 3:

[0124] Table 3

[0125] k <![CDATA[A2]]> <![CDATA[A3]]> <![CDATA[A4]]> <![CDATA[A5]]> <![CDATA[A6]]> <![CDATA[A7]]> <![CDATA[A8]]> L1S1 -50.32 0 9.69E-03 -1.13E-03 9.199E-05 -5.14E-06 1.83E-07 -3.18E-11 L1S2 -2.16 0 0.0217 -2.08E-03 1.49E-04 -5.87E-06 -3.66E-08 0 L5S1 -1.57 0 9.69E-03 -1.13E-03 -5.49E-6 0 0 0 L5S2 -100 0 0.0217 -2.08E-03 8.61E-06 0 0 0

[0126] Among them, the surface numbers L1S1 and L5S1 represent the object sides of the first lens L1 and the fifth lens L5 respectively, and the surface numbers L1S2 and L5S2 represent the image sides of the first lens L1 and the fifth lens L5 respectively.

[0127] It can be understood that the aspheres of the aspherical lenses in the receiving lens in this embodiment can use the aspheres constrained by the above aspherical formula, or can use the aspheres constrained by other aspherical formulas, and this application does not make a limitation.

[0128] Figure 2 Describes the MTF curve graph of the receiving lens designed in the lens combination mode of Embodiment 1.

[0129] Among them, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. The MTF curve graph can represent the modulation transfer of the lens imaging at different spatial frequencies under each field of view. As can be seen from Figure 2 the MTF curve graph in, during the process from the central field of view to the edge field of view, the MTF curve decreases uniformly and smoothly, indicating that the receiving lens has good imaging resolution ability in both low-frequency and high-frequency cases.

[0130] Figure 3 The field curvature graph and distortion graph of the receiving lens designed in the form of the lens combination in Embodiment 1 are described in sequence from left to right.

[0131] Specifically, in the field curvature graph, the abscissa represents the offset (unit: mm), and the ordinate represents the field angle (unit: degree). Among them, the S curve represents the sagittal field curvature at a wavelength of 940 nm, and the T curve represents the meridional field curvature at a wavelength of 940 nm. As can be seen from the field curvature graph, the field curvature of the receiving lens in this embodiment is within 0.03 mm, indicating that the field curvature and astigmatism of each field of view are well corrected, so that both the center and the edge of the field of view can have clear imaging.

[0132] In the distortion graph, the abscissa represents the distortion value (unit: %), and the ordinate represents the field angle (unit: degree). As can be seen from the distortion graph, the optical distortion of each field of view is within 5%, indicating that the image deformation caused by the principal beam is small, making the imaging quality of the system in an excellent state.

[0133] Figure 4 The SPOT SIZE graph (spot size graph) of the receiving lens designed in the form of the lens combination in Embodiment 1 is described. The SPOT SIZE graph is mainly used to evaluate the distribution size and shape of the spot on the image plane, and reflects the focusing ability of the system for a point light source or the influence of aberrations (such as spherical aberration, coma, astigmatism, etc.). In the SPOT SIZE graph, the root mean square distance (RMS Radius) of all traced rays to the center of the spot in the infrared band is controlled within 7 μm.

[0134] To sum up, the optical lens in this embodiment can correct spherical aberration and distortion by using aspherical lenses, reduce the number of lenses required for a large image plane under a large field of view angle. At the same time, the physical aperture of the five groups of lenses generally shows a decreasing trend along the optical axis direction, which can achieve the miniaturized design of the lens. In addition, through the combination of positive and negative optical powers, the lens can effectively control the light path, achieve a large working distance, and meet the requirements of large aperture, small size, and high resolution ability while ensuring that the receiving lens meets the large field of view angle.

[0135] Embodiment 2:

[0136] Such as Figure 5As shown in the figure, a receiving lens provided by the present invention is shown. In this embodiment, the receiving lens includes a first lens L1 with a negative focal power, a second lens L2 with a negative focal power, an aperture stop STO, a third lens L3 with a positive focal power, a fourth lens L4 with a positive focal power, a fifth lens L5 with a positive focal power, and a filter IR arranged in sequence along the optical axis direction. The lens forms an image on the image plane IMG.

[0137] In terms of shape and structure, the first lens L1 is a meniscus aspherical lens, the second lens L2 is a meniscus spherical lens, the third lens L3 is an aspherical lens with convex surfaces on both the object side and the image side, the fourth lens L4 is a meniscus spherical lens, and the fifth lens L5 is a spherical lens with convex surfaces on both the object side and the image side; among them, both the object side and the image side of the first lens L1 are rotationally symmetric aspheres, and both the object side and the image side of the third lens L3 are rotationally symmetric aspheres.

[0138] In terms of physical dimensions, the physical semi-apertures of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are 4.41 mm, 1.72 mm, 2.29 mm, 4.56 mm, and 4.60 mm in sequence.

[0139] In terms of optical parameters, the total effective focal length f of the lens is 2.36 mm, the entrance pupil diameter is 2 mm, the true semi-image height IH corresponding to the maximum field of view angle is 2.31 mm, and the ratio of the optical total length TTL to the true semi-image height IH corresponding to the maximum field of view angle is 9.91.

[0140] Specifically, the specific parameters and the base materials used for each lens in the receiving lens of this embodiment are shown in Table 4:

[0141] Table 4

[0142]

[0143]

[0144] In Table 4, the base materials of each lens are all selected as high-temperature resistant glass materials, so that the lens can be applied to high-temperature environments, such as in-vehicle environments. At the same time, considering that the first lens L1 may be exposed to the air, a lens made of D-LAK6 material with high hardness and low wear degree is selected. In addition, the assembly eccentricity of the fifth lens L5 is more sensitive to the performance. Therefore, single-head mounting is adopted in the design, so that its assembly eccentricity and tilt amount can be better controlled during the manufacturing process, thereby reducing the requirements for the manufacturing process and improving the production yield, achieving the purpose of cost reduction.

[0145] In this embodiment, the aspheric surfaces of the aspheric lenses (the first lens L1 and the third lens L3) satisfy the following aspheric formula:

[0146]

[0147] where Z is the sagittal height, c is the reciprocal of the radius of curvature R, y is the radial coordinate, k is the conic quadratic coefficient, and A2, A3, A4, A5, A6, A7, A8 are the aspheric high-order coefficients. The specific aspheric parameters of the first lens L1 and the third lens L3 are shown in Table 5:

[0148] Table 5

[0149]

[0150] where the surface numbers L1S1 and L3S1 represent the object sides of the first lens L1 and the third lens L3 respectively, and the surface numbers L1S2 and L3S2 represent the image sides of the first lens L1 and the third lens L3 respectively.

[0151] It can be understood that the aspheric surfaces of the aspheric lenses in the receiving lens in this embodiment can use the aspheric surfaces constrained by the above aspheric formula, or can use the aspheric surfaces constrained by other aspheric formulas, which is not limited in this application.

[0152] Figure 6 Describes the MTF curve graph of the receiving lens designed in the lens combination mode of Embodiment 2.

[0153] where the horizontal axis represents the spatial frequency (unit: lp / mm), the vertical axis represents the MTF value, and the MTF curve graph can represent the modulation transfer function of the lens imaging at different spatial frequencies under each field of view. From Figure 6 the MTF curve graph in, it can be seen that the MTF curve decreases uniformly and smoothly from the center to the edge field of view, indicating that the receiving lens has good imaging resolution ability in both low-frequency and high-frequency cases.

[0154] Figure 7 Sequentially describes the field curvature graph and the distortion graph of the receiving lens designed in the lens combination mode of Embodiment 2 from left to right.

[0155] Specifically, in the field curvature graph, the abscissa represents the offset (unit: mm), and the ordinate represents the field of view angle (unit: degree). Among them, the S curve represents the sagittal field curvature at a wavelength of 940 nm, and the T curve represents the meridional field curvature at a wavelength of 940 nm. It can be seen from the field curvature graph that the field curvature of the receiving lens in this embodiment is within 0.03 mm, indicating that the field curvature and astigmatism of each field of view have been well corrected, so that both the center and the edge of the field of view can have clear imaging.

[0156] In the distortion diagram, the abscissa represents the distortion value (unit: %), and the ordinate represents the field angle (unit: degree). It can be seen from the distortion diagram that the optical distortion of each field is within 4.8%, indicating that the image deformation caused by the principal beam is small, making the imaging quality of the system excellent.

[0157] Figure 8 The SPOT SIZE diagram (spot size diagram) of the receiving lens designed in the lens combination mode of Embodiment 1 is described. The SPOT SIZE diagram is mainly used to evaluate the distribution size and shape of the spot on the image plane, and reflects the focusing ability of the system for point light sources or the influence of aberrations (such as spherical aberration, coma, astigmatism, etc.). In the SPOT SIZE diagram, the root mean square distance (RMS Radius) from all traced rays to the center of the spot in the infrared band is controlled within 4.5μm.

[0158] In summary, the optical lens in this embodiment can correct spherical aberration and distortion by using aspherical lenses, reduce the number of lenses required for a large image plane at a large field angle, and at the same time, the physical apertures of the five groups of lenses generally show a decreasing trend along the optical axis direction, enabling the miniaturized design of the lens. In addition, through the combination of positive and negative optical powers, the lens can effectively control the light path, achieve a large working distance, and meet the requirements of large aperture, small size, and high resolution while ensuring that the receiving lens meets the large field angle.

[0159] Embodiment 3:

[0160] As Figure 9 shown, a receiving lens provided by the present invention. In this embodiment, the receiving lens includes a first lens L1 with negative optical power, an aperture stop STO, a second lens L2 with positive optical power, a third lens L3 with negative optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with positive optical power, and a filter IR arranged in sequence along the optical axis direction, and the lens forms an image on the image plane IMG.

[0161] In terms of shape and structure, the first lens L1 is a meniscus aspherical lens, the second lens L2 is a meniscus spherical lens, the third lens L3 is a meniscus aspherical lens, the fourth lens L4 is a meniscus spherical lens, and the fifth lens L5 is a meniscus spherical lens; among them, both the object side and the image side of the first lens L1 are rotationally symmetric aspheres, and both the object side and the image side of the third lens L3 are rotationally symmetric aspheres.

[0162] In terms of physical dimensions, the physical semi-apertures of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are 4.95mm, 2mm, 3.8mm, 4.8mm, and 4.44mm in sequence.

[0163] In terms of optical parameters, the total effective focal length f of the lens is 2.39 mm, the entrance pupil diameter is 2.1 mm, the true semi-image height IH corresponding to the maximum field of view angle is 2.31 mm, and the ratio of the total optical length TTL to the true semi-image height IH corresponding to the maximum field of view angle is 10.01.

[0164] Specifically, the specific parameters of each lens in the receiving lens in this embodiment and the substrate materials used are shown in Table 6:

[0165] Table 6

[0166]

[0167] In Table 6, the substrate materials of each lens are all selected as high-temperature-resistant glass materials, so that the lens can be applied to high-temperature environments, such as in-vehicle environments. At the same time, considering that the first lens L1 may be exposed to the air, a lens made of D-LAK6 material with high hardness and low abrasion is selected. In addition, the assembly eccentricity of the fifth lens L5 is more sensitive to the performance. Therefore, single-head mounting is adopted in the design, so that its assembly eccentricity and tilt amount can be better controlled during the manufacturing process, thereby reducing the requirements for the manufacturing process and improving the production yield, achieving the purpose of cost reduction.

[0168] In this embodiment, the aspheres of the aspherical lenses (the first lens L1 and the third lens L3) satisfy the following aspherical formula:

[0169]

[0170] Among them, Z is the sagittal height, c is the reciprocal of the radius of curvature R, y is the radial coordinate, k is the conic quadratic coefficient, and A2, A3, A4, A5, A6, A7, A8 are the aspherical high-order coefficients. The specific aspherical parameters of the first lens L1 and the third lens L3 are shown in Table 7:

[0171] Table 7

[0172]

[0173] Among them, the surface numbers L1S1 and L3S1 respectively represent the object sides of the first lens L1 and the third lens L3, and the surface numbers L1S2 and L3S2 respectively represent the image sides of the first lens L1 and the third lens L3.

[0174] It can be understood that the aspheres of each aspherical lens in the receiving lens in this embodiment can use the aspheres constrained by the above aspherical formula, or can use the aspheres constrained by other aspherical formulas, and this application does not make a limitation.

[0175] Figure 10Describes the MTF curve graph of the receiving lens designed in the lens combination mode of Embodiment III.

[0176] Among them, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. The MTF curve graph can represent the modulation transfer of the lens imaging at different spatial frequencies under each field of view. From Figure 10 the MTF curve graph in, it can be seen that during the process from the central to the peripheral field of view, the MTF curve decreases uniformly and smoothly. Especially under the condition of 111 lp / mm, the MTF is greater than 30%, which indicates that the lens has good imaging resolution ability in both low-frequency and high-frequency cases.

[0177] Figure 11 Describes the field curvature graph and distortion graph of the receiving lens designed in the lens combination mode of Embodiment I from left to right in sequence.

[0178] Specifically, in the field curvature graph, the abscissa represents the offset (unit: mm), and the ordinate represents the field of view angle (unit: degree). Among them, the S curve represents the sagittal field curvature at a wavelength of 940 nm, and the T curve represents the meridional field curvature at a wavelength of 940 nm. From the field curvature graph, it can be seen that the field curvature of the receiving lens in this embodiment is within 0.08 mm, indicating that the field curvature and astigmatism of each field of view are well corrected, so that both the center and the edge of the field of view can have clear imaging.

[0179] In the distortion graph, the abscissa represents the distortion value (unit: %), and the ordinate represents the field of view angle (unit: degree). From the distortion graph, it can be seen that the optical distortion of each field of view is within 4.6%, indicating that the image deformation caused by the principal beam is small, making the imaging quality of the system in an excellent state.

[0180] Figure 12 Describes the SPOT SIZE graph (spot size graph) of the receiving lens designed in the lens combination mode of Embodiment I. The SPOT SIZE graph is mainly used to evaluate the distribution size and shape of the spot on the image plane, and reflects the focusing ability of the system for a point light source or the influence of aberrations (such as spherical aberration, coma, astigmatism, etc.). In the SPOT SIZE graph, the root mean square distance (RMS Radius) from all traced rays to the center of the spot in the infrared band is controlled within 4.2 μm.

[0181] In summary, the optical lens in this embodiment can correct spherical aberration and distortion by using aspherical lenses, can reduce the number of lenses required for a large image plane under a large field of view angle. At the same time, the physical apertures of the five groups of lenses generally show a decreasing trend along the optical axis direction, and the miniaturized design of the lens can be achieved. In addition, through the combination of positive and negative optical powers, the lens can effectively control the light trend and achieve a large working distance. While ensuring that the receiving lens meets the requirements of a large field of view angle, it also meets the requirements of a large aperture, small size, and high resolution ability.

[0182] Embodiment 4:

[0183] As Figure 13 shown, a receiving lens provided by the present invention is shown. In this embodiment, the receiving lens includes a first lens L1 with a negative optical power, an aperture stop STO, a second lens L2 with a negative optical power, a third lens L3 with a positive optical power, a fourth lens L4 with a positive optical power, a fifth lens L5 with a positive optical power, and a filter IR arranged in sequence along the optical axis direction. The lens forms an image on the image plane IMG.

[0184] In terms of shape and structure, the first lens L1 is a meniscus aspherical lens, the second lens L2 is a meniscus spherical lens, the third lens L3 is a meniscus aspherical lens, the fourth lens L4 is a meniscus spherical lens, and the fifth lens L5 is a plano-convex spherical lens; wherein, both the object side and the image side of the first lens L1 are rotationally symmetric aspheres, and both the object side and the image side of the third lens L3 are rotationally symmetric aspheres.

[0185] In terms of physical dimensions, the physical semi-apertures of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are 6.34 mm, 1.72 mm, 3.2 mm, 4.8 mm, and 4.9 mm in sequence.

[0186] In terms of optical parameters, the total effective focal length f of the lens is 2.39 mm, the entrance pupil diameter is 1.9 mm, the true semi-image height IH corresponding to the maximum field of view angle is 2.31 mm, and the ratio of the optical total length TTL to the true semi-image height IH corresponding to the maximum field of view angle is 10.83.

[0187] Specifically, the specific parameters and the base materials used for each lens in the receiving lens of this embodiment are shown in Table 8:

[0188] Table 8

[0189]

[0190] In Table 8, the base materials of each lens are all selected as high-temperature-resistant glass materials, so that the lens can be applied to high-temperature environments, such as in-vehicle environments. At the same time, considering that the first lens L1 may be exposed to the air, a lens made of D-LAK6 material with high hardness and low abrasion is selected. In addition, the assembly eccentricity of the fifth lens L5 is more sensitive to the performance. Therefore, single-head mounting is adopted in the design, so that its assembly eccentricity and tilt amount can be better controlled during the manufacturing process, thereby reducing the requirements for the manufacturing process and improving the production yield, achieving the purpose of cost reduction.

[0191] In this embodiment, the aspheric surfaces of the aspheric lenses (the first lens L1 and the third lens L3) satisfy the following aspheric formula:

[0192]

[0193] where Z is the sagittal height, c is the reciprocal of the radius of curvature R, y is the radial coordinate, k is the conic coefficient, A2, A3, A4, A5, A6, A7, A8 are the aspheric high-order coefficients. The specific aspheric parameters of the first lens L1 and the third lens L3 are shown in Table 9:

[0194] Table 9

[0195]

[0196] where the surface numbers L1S1 and L3S1 respectively represent the object sides of the first lens L1 and the third lens L3, and the surface numbers L1S2 and L3S2 respectively represent the image sides of the first lens L1 and the third lens L3.

[0197] It can be understood that the aspheric surfaces of the aspheric lenses in the receiving lens in this embodiment can use the aspheric surfaces constrained by the above aspheric formula, or can use the aspheric surfaces constrained by other aspheric formulas, which is not limited in this application.

[0198] Figure 14 Describes the MTF curve graph of the receiving lens designed in the lens combination mode of Embodiment 3.

[0199] where the horizontal axis represents the spatial frequency (unit: lp / mm), the vertical axis represents the MTF value, and the MTF curve graph can represent the modulation transfer function of the lens imaging at different spatial frequencies under each field of view. From Figure 14 the MTF curve graph in it, it can be seen that during the process from the central field of view to the edge field of view, the MTF curve drops uniformly and smoothly. Especially under the condition of 111 lp / mm, the MTF is greater than 30%, which indicates that the lens has good imaging resolution ability in both low-frequency and high-frequency cases.

[0200] Figure 15 Sequentially describes the field curvature graph and the distortion graph of the receiving lens designed in the lens combination mode of Embodiment 1 from left to right.

[0201] Specifically, in the field curvature graph, the abscissa represents the offset (unit: mm), and the ordinate represents the field of view angle (unit: degree). Among them, the S curve represents the sagittal field curvature at a wavelength of 940 nm, and the T curve represents the meridional field curvature at a wavelength of 940 nm. From the field curvature graph, it can be seen that the field curvature of the receiving lens in this embodiment is within 0.08 mm, indicating that the field curvature and astigmatism of each field of view have been well corrected, so that both the center and the edge of the field of view can have clear imaging.

[0202] In the distortion graph, the abscissa represents the distortion value (unit: %), and the ordinate represents the field angle (unit: degree). It can be seen from the distortion graph that the optical distortion of each field is within 4.8%, indicating that the image deformation caused by the principal beam is small, and the imaging quality of the system is excellent.

[0203] Figure 16 The SPOT SIZE graph (spot size graph) of the receiving lens designed in the lens combination method of Embodiment 1 is described. The SPOT SIZE graph is mainly used to evaluate the distribution size and shape of the spot on the image plane, and reflects the focusing ability of the system for point light sources or the influence of aberrations (such as spherical aberration, coma, astigmatism, etc.). In the SPOT SIZE graph, the root mean square distance (RMS Radius) from all traced rays to the center of the spot in the infrared band is controlled within 4.2 μm.

[0204] In summary, the optical lens in this embodiment can correct spherical aberration and distortion by using aspherical lenses, reduce the number of lenses required for a large image plane at a large field angle, and at the same time, the physical aperture of the five groups of lenses generally shows a decreasing trend along the optical axis direction, which can achieve the miniaturized design of the lens. In addition, through the combination of positive and negative optical powers, the lens can effectively control the light path, achieve a large working distance, and meet the requirements of large aperture, small size, and high resolution while ensuring that the receiving lens meets the large field angle.

[0205] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0206] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A receiving lens, characterized in that, The receiving lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence along the optical axis direction; The object side and the image side of the first lens are both rotationally symmetric aspheres, and the object side and the image side of the fifth lens are both rotationally symmetric aspheres. The optical powers of the five groups of lenses are negative optical power, positive optical power, negative optical power, positive optical power, and positive optical power in sequence along the arrangement direction; Alternatively, the object side and the image side of the first lens are both rotationally symmetric aspheres, and the object side and the image side of the third lens are both rotationally symmetric aspheres. The optical powers of the five groups of lenses are negative optical power, negative optical power, positive optical power, positive optical power, and positive optical power in sequence along the arrangement direction; Among them, the base materials of the five groups of lenses are all high-temperature resistant materials; The receiving lens also satisfies the following optical parameter conditions: 0.3 < |f1 / f2| < 1.6; 0.3 < |f2 / f3| < 2.5; 0.2 < |f3 / f4| < 2.55; 0.4 < |f4 / f5| < 1.8; 20 ≤ TTL ≤ 25.5; 90° < FOV < 120°; Among them, f1, f2, f3, f4, and f5 are the effective focal lengths of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens respectively. TTL is the total optical length of the receiving lens, in millimeters, and FOV is the field of view angle of the receiving lens.

2. The receiving lens according to claim 1, wherein The receiving lens also includes an aperture stop; Among them, when the object side and the image side of the first lens are both rotationally symmetric aspheres, and the object side and the image side of the fifth lens are both rotationally symmetric aspheres, the aperture stop is arranged between the first lens and the second lens; when the object side and the image side of the first lens are both rotationally symmetric aspheres, and the object side and the image side of the third lens are both rotationally symmetric aspheres, the aperture stop is arranged between the second lens and the third lens.

3. The receiving lens according to claim 2, characterized in that, The receiving lens satisfies the following optical parameter conditions: 0.45 < SL / TTL < 0.85; Among them, SL is the distance from the aperture stop to the image plane of the receiving lens, in millimeters.

4. The receiving lens according to claim 1, characterized in that, The receiving lens satisfies the following optical parameter conditions: 0.125 < BFL / TTL < 0.195; Among them, BFL is the distance on the optical axis from the image side of the fifth lens to the image plane of the receiving lens, in millimeters.

5. The receiving lens according to claim 1, characterized in that, The receiving lens satisfies the following optical parameter conditions: 13.5° ≤ θ ≤ 15°; Among them, θ is the maximum chief ray incident angle of the image plane of the receiving lens.

6. The receiving lens according to claim 1, characterized in that, The receiving lens satisfies the following optical parameter conditions: 2.1≤f≤3.5； Among them, f is the total effective focal length of the receiving lens, in millimeters.

7. The receiving lens according to claim 6, wherein, The receiving lens satisfies the following optical parameter conditions: 9 ≤ TTL / IH ≤ 13; Among them, IH is the semi-image height of the target surface of the receiving lens.

8. The receiving lens according to claim 1, characterized in that The receiving lens satisfies the following optical parameter conditions: 9 ≤ SD1 ≤ 10; 4 ≤ SD5 ≤ 10; Among them, SD1 is the physical aperture of the first lens, and SD5 is the physical aperture of the fifth lens, in millimeters.

9. The receiving lens according to claim 8, characterized in that, The receiving lens meets the following optical parameter conditions: 1.15 ≤ Fno ≤ 1.23; wherein, Fno is the aperture size of the receiving lens.

10. The receiving lens according to any one of claims 1 to 9, characterized in that, The working wavelength band of the receiving lens is 905 nm to 950 nm, and the main wavelength is 940 nm.

Images