Infrared collimating lens

Abstract

The utility model discloses an infrared collimating lens, which comprises a lens cone, an internal component arranged in the lens cone, and a first locking piece and a second locking piece which are respectively arranged at two ends of the internal component and fix the internal component in the lens cone, the internal assembly sequentially comprises a first lens, a first spacer, a second lens, a third lens, a second spacer and a fourth lens from the object side to the image side along the optical axis. According to the utility model, one of the four lenses is a plastic lens, so that the cost, the total length and the weight can be reduced as much as possible while the collimation effect is ensured. Specifically, the aspheric plastic lens is adopted to realize correction of various aberrations of light, light emitted by a laser radar is collimated into parallel light, an infrared light collimation effect is better realized, and through reasonable distribution of focal power and surface types of each lens, the collimation capability of the lens is effectively improved, and the infrared collimation lens with high reliability and low cost is obtained.

Description

Technical Field

[0001] The utility model relates to the technical field of optical imaging, in particular to an infrared collimating lens. Background Art

[0002] LiDAR is a radar system that emits laser beams to detect the position, speed, etc. of a target. In recent years, with the popularity of LiDAR, the demand for collimating lenses installed on radars has been increasing. As they are used in various complex scenarios, the reliability requirements for lenses are also getting higher and higher.

[0003] The most promising laser radar in the future is the FMCW laser radar using C-band (1530nm~1565nm) laser. Laser radar is generally used in complex working environments such as vehicles, roadsides and mines. The large number of application scenarios has led to an increasing demand for lenses, so reducing lens costs and improving lens reliability are urgent issues that infrared collimating lenses need to solve. Therefore, a low-cost, high-reliability infrared collimating lens is urgently needed. Summary of the invention

[0004] The purpose of the present application is to provide an infrared collimating lens for solving the problem of low-cost, high-reliability infrared collimating lens currently in urgent need and applied to laser radar using C-band (1530nm~1565nm) laser.

[0005] In a first aspect, the present application provides an infrared collimating lens, comprising a lens barrel, an internal component disposed in the lens barrel, and a first locking member and a second locking member respectively disposed at two ends of the internal component to fix the internal component in the lens barrel;

[0006] The internal components include: a first lens, a first spacer, a second lens, a third lens, a second spacer and a fourth lens in order from the object side to the image side along the optical axis.

[0007] In one embodiment of the present application, the first lens has positive focal power; the second lens has negative focal power; the third lens has positive focal power; the fourth lens has positive focal power; and the smallest diameter point between the second lens and the third lens in the lens barrel is set as an aperture stop.

[0008] In one embodiment of the present application, the inner diameter of the second lens limiting step surface in the lens barrel is d0s, the inner diameter at the aperture is d0, the distance from the second lens limiting step surface in the lens barrel to the aperture is h0', the radius of curvature of the image side of the second lens is R4, and the infrared collimating lens satisfies: 0.50<(d0s-d0) / (h0'*R4)<2.0.

[0009] In one embodiment of the present application, the third lens is an aspherical plastic lens; the axial distance from the object side of the first lens to the image plane of the infrared collimating lens is TTL, and the infrared collimating lens satisfies: 25mm <TTL<30mm。

[0010] In one embodiment of the present application, the inner diameter of the object side of the first locking piece is d1s, the inner diameter of the image side of the first locking piece is d1m, the height of the inclined surface of the first locking piece is h1', the radius of curvature of the object side of the first lens is R1, and the first locking piece and the first lens satisfy 0.27<5*(d1s-d1m) / (h1'*R1)<0.42.

[0011] In one embodiment of the present application, the distance between the image side of the first locking member and the second lens limiting step surface in the lens barrel is EP10, the center thickness of the first lens on the optical axis is CT1, the center thickness of the second lens on the optical axis is CT2, and the infrared collimating lens satisfies: 0.42 <EP10 / (CT1+CT2)<0.85。

[0012] In one embodiment of the present application, the distance between the side surface of the second locking member and the limiting step surface of the third lens in the lens barrel is EP40, the center thickness of the third lens on the optical axis is CT3, the center thickness of the fourth lens on the optical axis is CT4, and the infrared collimating lens meets the following conditions: 0.50 <EP40 / (CT4+CT3)<0.95。

[0013] In one embodiment of the present application, the radius of curvature of the object side of the second lens is R3, the inner diameter of the image side of the first spacer is d2m, and the second lens and the first spacer satisfy: 0.50<R3 / d2m<1.00.

[0014] In one embodiment of the present application, the height of the first spacer is h2, the center thickness of the first lens on the optical axis is CT1, the center thickness of the second lens on the optical axis is CT2, and the infrared collimating lens satisfies: 0.15<h2 / (CT1+CT2)<0.5.

[0015] In one embodiment of the present application, the axial distance from the object side of the first lens to the image side of the fourth lens is TD, the maximum height of the lens barrel is H, the sum of the axial thickness of each lens is ∑CT, the sum of the height of each spacer is ∑h, and the infrared collimating lens satisfies: 0.2<(TD / ∑CT)×(∑h / H)<1.5.

[0016] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0017] The infrared collimating lens provided by the embodiment of the utility model is used, and one of the four lenses is a plastic lens. While ensuring the collimation effect, the cost, total length and weight can be reduced as much as possible. Specifically, aspheric plastic lenses are used to correct various aberrations of light, and the light emitted by the laser radar is collimated into parallel light, so as to better achieve the collimation effect of infrared light. By reasonably allocating the optical focal length and surface shape of each lens, the collimation ability of the lens is effectively improved, and a low-cost infrared collimating lens with high reliability is obtained. The design wavelength of the infrared collimating lens provided by the utility model is 1528nm~1568nm. It can be installed in the transmitting and receiving system of the laser radar to transmit and receive infrared lasers.

[0018] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by implementing the utility model. The purpose and other advantages of the utility model can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 Shown is a schematic diagram of the lens structure of an infrared collimating lens with size markings according to an embodiment of the present application.

[0021] Figure 2 Shown is a structural schematic diagram of a spacer in an infrared collimating lens according to an embodiment of the present application.

[0022] Figure 3 A lens cross-sectional diagram of a specific example of an infrared collimating lens according to an embodiment of the present application is shown.

[0023] Figure 4 Display as Figure 3 Schematic diagram of the lens structure of the structural lens shown.

[0024] Figure 5 Shown is a light path diagram of each field of view light of the infrared collimating lens described in an embodiment of the present application hitting the image plane.

[0025] Among them, 21 is a lens barrel, 22 is a first locking member, 23 is a first spacer, 24 is a second spacer, 25 is a second locking member, L1 is a first lens, L2 is a second lens, L3 is a third lens, and L4 is a fourth lens. DETAILED DESCRIPTION

[0026] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0027] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application, and thus the drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0028] The following embodiments of the present application provide an infrared collimating lens for solving the problem of the currently urgently needed low-cost, high-reliability infrared collimating lens for use in laser radars using C-band (1530nm~1565nm) lasers.

[0029] The principle and implementation of an infrared collimating lens of this embodiment will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can understand the infrared collimating lens of this embodiment without creative work.

[0030] refer to Figure 1 As shown, this embodiment provides an infrared collimating lens, including a lens barrel 21, an internal component, and a first locking member 22 and a second locking member 25. The internal component is sleeved in the lens barrel 21, and the first locking member 22 and the second locking member 25 are respectively arranged at both ends of the internal component, for fastening the internal component arranged in the lens barrel 21.

[0031] The internal components include a lens part and a spacer part, the lens part includes four lenses, and the spacer part includes two spacers. Further, the internal components include: a first lens L1, a first spacer 23, a second lens L2, a third lens L3, a second spacer 24 and a fourth lens L4 in order from the object side to the image side along the optical axis. That is, the first spacer 23 is arranged between the first lens L1 and the second lens L2 to control the distance between the first lens L1 and the second lens L2; ​​the second spacer 24 is arranged between the third lens L3 and the fourth lens L4 to control the distance between the third lens L3 and the fourth lens L4. The first locking member 22 is arranged on the object side of the first lens L1, and the second locking member 25 is arranged on the image side of the fourth lens L4. The first locking member 22 and the second locking member 25 are both connected to the lens barrel 21 in a detachable locking manner. The first locking member 22 and the second locking member 25 of the above-mentioned parts are matched and fixed in the lens barrel 21.

[0032] like Figure 2 As shown, each spacer and each locking member can be set as an annular shape. The inner side of the annular spacer can be provided with an inclined surface based on requirements. At the same time, the inner and outer diameters and height of the annular spacer are set based on the lens design requirements and the required lens spacing involved, etc. The outer side surface of the annular locking member is provided with an external thread, and internal threads are provided at corresponding positions inside the object side end and the image side end of the lens barrel 21. The lens barrel 21 is fixedly connected to the first locking member 22 and the second locking member 25 through threads, and the lens barrel 21 can also be fixedly tightened to the first locking member 22 and the second locking member 25 based on other reasonable detachable methods. No fixed restrictions are imposed on this here.

[0033] In this embodiment, a plurality of lens limiting steps are provided inside the lens barrel 21. The position with the smallest diameter between the second lens L2 and the third lens L3 inside the lens barrel is set as the aperture stop of the infrared collimating lens in this embodiment. The aperture stop is mainly used to limit the light passing aperture of the beam on the axis of the infrared collimating lens. The infrared collimating lens in this embodiment also needs to satisfy: 25mm < TTL < 30mm, where TTL is the axial distance from the object side surface of the first lens L1 to the image plane of the infrared collimating lens. The above settings can control the length of the infrared collimating lens within a suitable range and avoid insufficient external space during use due to the excessive length of the infrared collimating lens.

[0034] In this embodiment, the following settings are also made for the infrared collimating lens. Specifically, the inner diameter of the limiting step surface of the second lens L2 inside the lens barrel 21 is d0s, the inner diameter at the aperture stop is d0, the distance from the limiting step surface of the second lens L2 inside the lens barrel 21 to the aperture stop is h0', and the radius of curvature of the image side surface of the second lens L2 is R4; at this time, the infrared collimating lens also needs to satisfy: 0.50 < (d0s - d0) / (h0' * R4) < 2.0. The above settings achieve the control of the entry of stray light through the aperture stop, thereby improving the imaging clarity; at the same time, according to the radius of curvature of the image side surface of the second lens L2 and the distance from the limiting step surface of the second lens L2 inside the lens barrel 21 to the object side surface of the aperture stop, the inner diameter of the limiting step surface of the second lens L2 inside the lens barrel 21 and the inner diameter of the aperture stop are set to control the dimensions near the aperture stop of the lens barrel 21 and prevent the inner wall from interfering with the transmission of the signal light.

[0035] In this embodiment, the following settings are also made for the first locking member 22 and the first lens L1. Specifically, the inner diameter of the object side of the first locking member 22 is set as d1s, the inner diameter of the image side of the first locking member 22 is set as d1m, the height of the inclined surface of the first locking member 22 is set as h1', and the radius of curvature of the object side of the first lens L1 is set as R1. At this time, it is set that the first locking member 22 and the first lens L1 satisfy: 0.27 < 5*(d1s - d1m) / (h1'*R1) < 0.42. The above settings control the entry of stray light through the inner diameter of the object side, the inner diameter of the image side, and the inclined surface dimensions of the first locking member 22, improving the imaging clarity; and by referring to the radius of curvature of the object side of the first lens L1 and the height of the inclined surface of the first locking member 22, the inner diameter of the object side and the inner diameter of the image side on both sides of the inclined surface of the first locking member 22 are set, controlling the size of the first locking member, which can achieve the purpose of preventing interference with the transmission of signal light on the inner wall.

[0036] In this embodiment, the following settings are also made for the first locking member 22 and the first lens L1. Specifically, the distance between the image side of the first locking member 22 and the limiting step surface of the second lens L2 in the lens barrel 21 is set as EP10, the central thickness of the first lens L1 on the optical axis is set as CT1, and the central thickness of the second lens L2 on the optical axis is set as CT2. At this time, it is set that the infrared collimating lens satisfies: 0.42 < EP10 / (CT1 + CT2) < 0.85. By adjusting the central thicknesses of the first lens L1 and the second lens L2, the processability of the lenses is improved; at the same time, designing the distance between the image side plane of the first locking member 22 and the limiting step surface of the second lens L2 in the lens barrel 21 within a reasonable range is beneficial for the first locking member 22 to block the stray light caused by the divergent light reflected from the object sides of the first lens L1 and the second lens L2, thereby improving the image quality and ensuring the assembly stability.

[0037] In this embodiment, the following settings are also made for the infrared collimating lens. Specifically, the distance between the object side of the second locking member 25 and the limiting step surface of the third lens L3 in the lens barrel 21 is set as EP40, the central thickness of the third lens L3 on the optical axis is set as CT3, and the central thickness of the fourth lens L4 on the optical axis is set as CT4. At this time, it is set that the infrared collimating lens satisfies: 0.50 < EP40 / (CT4 + CT3) < 0.95. The above settings can improve the processability of the lenses by adjusting the central thicknesses of the third lens L3 and the fourth lens L4; at the same time, designing the distance between the object side plane of the second locking member 25 and the limiting step surface of the third lens L3 in the lens barrel 21 within a reasonable range is beneficial for the second locking member 25 to block the stray light caused by the divergent light reflected from the image sides of the third lens L3 and the fourth lens L4, thereby improving the image quality and ensuring the assembly stability.

[0038] This embodiment also sets the second lens L2 and the first spacer 23 as follows: specifically, the curvature radius of the object side of the second lens L2 is set to R3, and the inner diameter of the image side of the first spacer 23 is set to d2m; at this time, the second lens L2 and the first spacer 23 are set to satisfy: 0.50<R3 / d2m<1.00. The above setting reasonably controls the curvature radius of the object side of the second lens L2 and the inner diameter of the image side of the first spacer 23, so that the first spacer 23 intercepts unnecessary non-imaging stray light without interfering with the signal light, thereby improving the imaging quality.

[0039] This embodiment also makes the following settings for the infrared collimating lens, specifically setting the height of the first spacer 23 to h2, the center thickness of the first lens L1 on the optical axis to CT1, and the center thickness of the second lens L2 on the optical axis to CT2; at this time, the infrared collimating lens is set to meet: 0.15<h2 / (CT1+CT2)<0.5. The above settings control the on-axis thickness of the first lens L1 and the second lens L2, so that the infrared collimating lens system has a smaller field curvature. And by controlling the height of the first spacer 23, the structural strength of the first spacer 23 is guaranteed, so as to achieve the purpose of enhancing the stability of the lens structure.

[0040] This embodiment also makes the following settings for the infrared collimating lens, specifically setting the on-axis distance from the object side of the first lens L1 to the image side of the fourth lens L4 to TD, the maximum height of the lens barrel 21 to H, the sum of the on-axis thickness of each lens to ∑CT, and the sum of the height of each spacer to ∑h; at this time, the infrared collimating lens is set to meet: 0.2<(TD / ∑CT)×(∑h / H)<1.5. The above setting controls the maximum height of the lens barrel 21 by controlling the on-axis distance from the object side of the first lens L1 to the image side of the fourth lens L4, thereby controlling the overall length of the lens and improving space utilization. At the same time, by reasonably setting the thickness of the spacer to control the distribution of the overall structure of the lens, reduce the difference in structure, improve stability in high temperature and high humidity environments, and improve product reliability.

[0041] The infrared collimating lens of this embodiment reduces the number of lenses to four by reasonably allocating the focal length and surface shape of each lens, while ensuring the collimating effect, in order to maximize the reliability of the lens and reduce the cost, so that each lens can fully play its role. Because the number of lenses is small, the total length of the system can also be reduced and the weight of the lens can be reduced.

[0042] Those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the infrared collimating lens can be changed to obtain the various results and advantages described in this specification. For example, although four lenses are described as an example in the embodiment, the infrared collimating lens is not limited to including four lenses, and the infrared collimating lens may also include other numbers of lenses if necessary.

[0043] In addition to the above-mentioned settings of each spacer and lens, each lens is also set as follows: the first lens L1 is set to have positive focal power; the second lens L2 has negative focal power; the third lens L3 has positive focal power; and the fourth lens L4 has positive focal power. Among them, the third lens L3 is an aspherical plastic lens; and except for the third lens L3, the other three lenses are set to glass lenses, that is, the infrared collimating lens of this embodiment is a 3G1P glass-plastic hybrid lens. The design wavelength range of the infrared collimating lens of this embodiment is 1528nm~1568nm.

[0044] Preferably, the glass lenses in the infrared collimating lens of this embodiment are made of H-ZLAF90, a material with an extremely high refractive index. The high refractive index enables the lens to have a sufficiently large impact on the optical path at a very short distance, thereby minimizing the length of the lens.

[0045] The infrared collimating lens of the embodiment of the utility model adopts a reverse design, that is, the actual light is emitted by the laser radar on the image side, and is collimated into a parallel beam by the lens and then emitted from the object side. The light reflected back after hitting the object is still received by this lens and then returns to the laser radar. The infrared collimating lens of this embodiment is a lens that can both emit and receive lasers.

[0046] Among them, the object side surface of the first lens L1 can be set as a convex surface, and the image side surface can be set as a concave surface, that is, the first lens L1 can be set as a convex-concave lens with positive optical power. Further, the first lens L1 can be set as a meniscus lens with positive optical power, and the high refractive index material H-ZLAF90 is used to make the light converge to the next lens next to it. Since the first lens L1 is located at the first position of the infrared collimating lens, it may be exposed to the external space during actual application, so high requirements are placed on its hardness, wear resistance, water resistance and acid resistance, and the selected material H-ZLAF90 can meet the above requirements.

[0047] The object side surface of the second lens L2 can be set to be a convex surface, and the image side surface can be set to be a concave surface, that is, the second lens L2 can be set to be a convex-concave lens with negative optical power. Further, the second lens L2 can be set to be an infrared lens with negative optical power, which is used to diverge the light and prevent the first lens from causing excessive convergence. The first lens L1 and the second lens cooperate with each other to make the light of each field of view converge at the aperture.

[0048] The object side of the third lens L3 can be set as a concave surface, and the image side can be set as a convex surface; that is, the third lens L3 can be set as an aspherical plastic lens with a positive optical power. The main purpose of the third lens L3 is to correct various aberrations, especially the spherical aberration generated by various spherical glasses, and it has the best effect when used near the aperture stop because the light rays converge at the aperture stop, and the third lens L3 can centrally correct the light ray aberrations of all fields of view. The design of the aspherical lens of the third lens L3 can approximately offset the effect of 3 spherical lenses in the infrared collimating lens. At the same time, the plastic itself is lighter, so the use of this aspherical lens can reduce the number of lenses in the lens. It not only reduces the total length of the entire lens but also reduces the weight of the lens. Further, it is also set that the infrared collimating lens satisfies: 5 < f3 / f < 20, where f3 is the effective focal length of the third lens L3, and f is the total effective focal length of the infrared collimating lens. By reasonably controlling the ratio of the effective focal length of the third lens L3 to the total effective focal length, the third lens L3 can reasonably share the optical power, better correct the spherical aberration, chromatic aberration, and other aberrations of the lens, and reduce the sensitivity of the lens to tolerances.

[0049] The object side of the fourth lens L4 can be set as a convex surface, and the image side can be set as a convex surface or a concave surface, that is, the fourth lens L4 can be set as a biconvex lens with a positive optical power, and can also be set as a convex-concave lens with a positive optical power. Further, the fourth lens L4 can use the H-ZLAF90 material with an ultra-high refractive index, and this lens provides a very large optical power, which can smoothly transmit the light rays to the corresponding field of view of the image plane. Even further, it is also set that the infrared collimating lens satisfies: -2 < f4 / R42 < 0, where f4 is the effective focal length of the fourth lens L4, and R42 is the radius of curvature of the image side of the fourth lens L4. Limiting the radius of curvature of the image side of the fourth lens L4 within a reasonable range can slow down the deflection of the light rays in the fourth lens L4, thereby reducing the sensitivity of the fourth lens L4, and at the same time reducing the spherical aberration generated by the fourth lens L4.

[0050] A protective glass is also provided between the fourth lens L4 and the image plane of the infrared collimating lens. The material of the protective glass can be set as quartz to protect the light exit of the emitting laser device.

[0051] Further, in this embodiment, it is also designed that the infrared collimating lens satisfies: 1 < TD / f < 1.5, where TD is the axial distance from the object side of the first lens L1 to the image side of the fourth lens L4, and f is the total effective focal length of the infrared collimating lens. This setting can, on the one hand, avoid the lens being too long, and on the other hand, while meeting the requirements of being thin and light, a larger focal length can be obtained, making the infrared collimating lens perform better.

[0052] The present embodiment also designs an infrared collimating lens to satisfy: 3<TD / ∑AT<4, where TD is the on-axis distance from the object side of the first lens L1 to the image side of the fourth lens L4, and ∑AT is the sum of the air gaps on the optical axis between any two adjacent lenses from the first lens L1 to the fourth lens L4. This setting can ensure the processing and assembly characteristics of the infrared collimating lens, avoid interference between the front and rear lenses during the assembly process due to too small a gap, and avoid problems such as the lens being too thin and difficult to form, and easy deformation during assembly.

[0053] The infrared collimating lens of this embodiment can be designed with different maximum collimating light spots based on actual needs. For example, the maximum collimating light spot diameter of the infrared collimating lens of this embodiment can be designed to be 8 mm. Figure 5 There is an amplification of the optical path of each field of view light to the image plane (when the light is actually emitted from the lidar, the main light is perpendicular to the image plane, and the upper and lower lights are symmetrically distributed relative to the main light.) Figure 5 As shown, for the design of the above-mentioned maximum collimated light spot, the incident light of the infrared collimating lens of this embodiment must meet the following conditions: ANG0<3°, ANG1>10°, ANG2>15°, where ANG0 is the maximum value of the angle between the main light of all fields of view of the infrared collimating lens and the normal line of the image plane, ANG1 is the minimum value of the angle between the upper light of all fields of view of the infrared collimating lens and the normal line of the image plane, and ANG2 is the minimum value of the angle between the lower light of all fields of view of the infrared collimating lens and the normal line of the image plane. The incident light of the infrared collimating lens that does not meet the above conditions cannot output a collimated light spot that meets the requirements.

[0054] The infrared collimating lens of this embodiment reduces the number of lenses to four by reasonably allocating the focal length and surface shape of each lens, while ensuring the collimating effect, in order to maximize the reliability of the lens and reduce the cost, so that each lens can fully play its role. Because the number of lenses is small, the total length of the system can also be reduced and the weight of the lens can be reduced.

[0055] Those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the infrared collimating lens can be changed to obtain the various results and advantages described in this specification. For example, although four lenses are described as an example in the embodiment, the infrared collimating lens is not limited to including four lenses, and the infrared collimating lens may also include other numbers of lenses if necessary.

[0056] Figure 1In the figure, D0 represents the outer diameter of the lens barrel; d0s represents the inner diameter of the second lens limiting step surface in the lens barrel; d0 represents the inner diameter of the aperture in the lens barrel; h0' represents the distance from the second lens limiting step surface in the lens barrel to the object side of the aperture; H represents the maximum height of the lens barrel; d1s represents the inner diameter of the object side of the first locking piece; d1m represents the inner diameter of the image side; h1 represents the height of the first locking piece; h1' represents the height of the inclined surface of the first locking piece; h2 represents the height of the first spacer; D2 represents the outer diameter of the first spacer; d2m represents the inner diameter of the image side of the first spacer; h3 represents the height of the second spacer; h4 represents the height of the second locking piece; d4 represents the inner diameter of the second locking piece.

[0057] A specific design example of the infrared collimating lens applicable to the above embodiment is further described below with reference to the above category schematic diagram.

[0058] Figure 3 A lens cross-sectional diagram of a specific example of an infrared collimating lens according to an embodiment of the present application is shown. Figure 4 Display as Figure 3 The lens structure diagram of the structural lens shown is as follows:

[0059] The first lens L1 has positive refractive power, its object side surface S1 is convex, and its image side surface S2 is concave;

[0060] The second lens L2 has negative refractive power, its object side surface S3 is convex, and its image side surface S4 is concave;

[0061] The third lens L3 has positive refractive power, its object-side surface S6 is concave, and its image-side surface S7 is convex;

[0062] The fourth lens L4 has positive refractive power, and its object-side surface S8 is convex, and its image-side surface S9 is convex;

[0063] The protective glass G8 has an object side surface S10 and an image side surface S11, and the incident light passes through each surface S1 to S11 in sequence and is finally imaged on the imaging surface IMA. STO represents an aperture, and OBJ represents an object plane.

[0064] TTL=28.9, where TTL is the axial distance from the object side of the first lens to the image plane of the infrared collimating lens.

[0065] As shown in Table 1, it is a table of basic parameters of the lens assembly of the infrared collimating lens of Example 1, wherein the units of the curvature radius, thickness, and total effective focal length are all in millimeters (mm).

[0066]

[0067] Table 1

[0068] The main value parameters in Example 1 are as follows: system image side F / # is 1.9, total effective focal length f / mm is 15.6, half FOV / ° is 10, entrance pupil diameter / mm is 8, image height IMH / mm is 5.6, and image side NA is 0.24.

[0069] The object-side surface S6 and the image-side surface S7 of the third lens are both aspherical surfaces. Table 2 shows the high-order coefficients A4, A6, A8 and A10 of the aspherical surface S6 and the aspherical surface S7 that can be used in Example 1.

[0070] Face number A4 A6 A8 A10 S6 -9.3E-04 -1.1E-05 -9.2E-07 1.6E-07 S7 -2.7E-04 2.4E-06 -1.7E-07 7.3E-09

[0071] Table 2

[0072] As shown in Table 3, it is a basic parameter table of the lens barrel 21 and the spacer etc. in the infrared collimating lens of the specific example 1.

[0073]

[0074]

[0075] The specific values ​​of some calculation parameters in the above table are:

[0076] The curvature radius R1 of the object side of the first lens is 9.76mm, the curvature radius R3 of the object side of the second lens is 8.13mm, the curvature radius R4 of the image side of the second lens is 4.21mm, the distance EP10 between the image side of the first locking piece and the object side of the second lens limiting step in the lens barrel is 3.84mm, the distance EP40 between the object side of the second locking piece and the object side of the third lens limiting step in the lens barrel is 6.75mm, the center thickness CT1 of the first lens on the optical axis is 2.86mm, the center thickness CT2 of the second lens on the optical axis is 2.51mm, the center thickness CT3 of the third lens on the optical axis is 3.99mm, the center thickness CT4 of the fourth lens on the optical axis is 4mm, the axial distance TD from the object side of the first lens to the image side of the fourth lens is 19.28mm, the sum of the axial thickness ∑CT of each lens is 13.36mm, and the sum of the height ∑h of each spacer is 11.73mm.

[0077] The infrared collimating lens in Example 1 meets the following requirements:

[0078] f3 / f=11.159, where f3 is the effective focal length of the third lens, and f is the total effective focal length of the infrared collimating lens.

[0079] f4 / R42=-1, wherein f4 is the effective focal length of the fourth lens, and R42 is the radius of curvature of the image side surface of the fourth lens.

[0080] TD / f=1.2, where TD is the axial distance from the object side of the first lens to the image side of the fourth lens, and f is the total effective focal length of the infrared collimating lens.

[0081] TD / ∑AT=3.256, where TD is the axial distance from the object side of the first lens to the image side of the fourth lens, and ∑AT is the sum of the air intervals on the optical axis between any two adjacent lenses from the first lens to the fourth lens.

[0082] The infrared collimating lens in Example 1 maximizes the reliability of the lens while ensuring the collimation effect.

[0083] The infrared collimating lens provided in the embodiment of the utility model is provided with four lenses, one of which is a plastic lens. While ensuring the collimation effect, it can also reduce the cost, reduce the total length and reduce the weight as much as possible. Specifically, aspherical plastic lenses are used to correct various aberrations of light, collimate the light emitted by the laser radar into parallel light, and better achieve the collimation effect of infrared light. By reasonably allocating the optical focal length and surface shape of each lens, the collimation ability of the lens is effectively improved, and a low-cost infrared collimating lens with high reliability is obtained. The design wavelength of the infrared collimating lens provided by the utility model is 1528nm~1568nm. It can be installed in the transmitting and receiving system of the laser radar to transmit and receive infrared lasers.

[0084] Although the embodiments disclosed in the present invention are as above, the above contents are only embodiments adopted for facilitating the understanding of the present invention, and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. An infrared collimating lens, characterized in that: It comprises a lens barrel, an internal component arranged in the lens barrel, and a first locking member and a second locking member respectively arranged at two ends of the internal component to fix the internal component in the lens barrel; The internal components include, in order from the object side to the image side along the optical axis: a first lens, a first spacer, a second lens, a third lens, a second spacer and a fourth lens; the third lens is an aspherical plastic lens; the first lens has positive focal power; the second lens has negative focal power; the third lens has positive focal power; and the fourth lens has positive focal power.

2. The infrared collimating lens according to claim 1, characterized in that: The position with the smallest diameter between the second lens and the third lens in the lens barrel is set as an aperture stop.

3. The infrared collimating lens according to claim 2, characterized in that: The inner diameter of the second lens limiting step surface in the lens barrel is d0s, the inner diameter of the aperture is d0, the distance from the second lens limiting step surface in the lens barrel to the aperture is h0', the curvature radius of the image side of the second lens is R4, and the infrared collimating lens satisfies: 0.50<(d0s-d0) / (h0'*R4)<2.

0.

4. The infrared collimating lens according to claim 1, characterized in that: The axial distance from the object side of the first lens to the image plane of the infrared collimating lens is TTL, and the infrared collimating lens satisfies: 25mm <TTL<30mm。 5. The infrared collimating lens according to claim 1, characterized in that: The inner diameter of the object side of the first locking piece is d1s, the inner diameter of the image side of the first locking piece is d1m, the height of the inclined surface of the first locking piece is h1', the radius of curvature of the object side of the first lens is R1, and the first locking piece and the first lens satisfy 0.27<5*(d1s-d1m) / (h1'*R1)<0.

42.

6. The infrared collimating lens according to claim 1, characterized in that: The distance between the image side of the first locking member and the limiting step surface of the second lens in the lens barrel is EP10, the center thickness of the first lens on the optical axis is CT1, the center thickness of the second lens on the optical axis is CT2, and the infrared collimating lens meets: 0.42 <EP10 / (CT1+CT2)<0.85。 7. The infrared collimating lens according to claim 1, characterized in that: The distance between the side surface of the second locking member and the limiting step surface of the third lens in the lens barrel is EP40, the center thickness of the third lens on the optical axis is CT3, the center thickness of the fourth lens on the optical axis is CT4, and the infrared collimating lens meets: 0.50 <EP40 / (CT4+CT3)<0.95。 8. The infrared collimating lens according to claim 1, characterized in that: The curvature radius of the object side of the second lens is R3, the inner diameter of the image side of the first spacer is d2m, and the second lens and the first spacer satisfy: 0.50<R3 / d2m<1.

00.

9. The infrared collimating lens according to claim 1, characterized in that: The height of the first spacer is h2, the center thickness of the first lens on the optical axis is CT1, the center thickness of the second lens on the optical axis is CT2, and the infrared collimating lens satisfies: 0.15<h2 / (CT1+CT2)<0.

5.

10. The infrared collimating lens according to claim 1, characterized in that: The axial distance from the object side of the first lens to the image side of the fourth lens is TD, the maximum height of the lens barrel is H, the sum of the axial thickness of each lens is ∑CT, the sum of the height of each spacer is ∑h, and the infrared collimating lens satisfies: 0.2<(TD / ∑CT)×(∑h / H)<1.5.

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