CN117970613A

CN117970613A - Large aperture infrared collimation lens

Info

Publication number: CN117970613A
Application number: CN202410371942.4A
Authority: CN
Inventors: 蒋文超; 龚鸿若; 单子豪; 黄锦熙
Original assignee: Hangzhou Opto Semiconductor Technology Co ltd
Current assignee: Hangzhou Opto Semiconductor Technology Co ltd
Priority date: 2024-03-29
Filing date: 2024-03-29
Publication date: 2024-05-03
Anticipated expiration: 2044-03-29

Abstract

The invention discloses a large-aperture infrared collimating lens, which sequentially comprises the following components from an object side to an image side along an optical axis: a first lens having positive optical power; a second lens having positive optical power; a third lens having negative optical power; a fourth lens having positive optical power; a fifth lens having negative optical power; a sixth lens having positive optical power; a seventh lens having negative optical power; the object side surface of the fifth lens is glued with the image side surface of the fourth lens, and the object side surface of the seventh lens is glued with the image side surface of the sixth lens; the total effective focal length of the large-aperture infrared collimating lens is f, the entrance pupil diameter of the large-aperture infrared collimating lens is EPD, and the requirements are met: 1.0< f/EPD <1.5. The invention can lead the lens to collimate the laser with large numerical aperture, obtain better collimation effect, is suitable for the laser radar using C-band (1530nm-1565 nm) laser and meets the requirement of long-distance detection of scenes.

Description

Large aperture infrared collimation lens

Technical Field

The invention relates to the technical field of optical imaging, in particular to a large-aperture infrared collimating lens.

Background

Lidar is a radar system that emits a laser beam to detect the position, speed, etc. of a target. The most potential laser radar in the future is an FMCW laser radar using C-band (1530nm-1565nm) laser, however, a large aperture infrared collimating lens matching the band is very rare in the market.

When the laser radar is applied to long-distance detection scenes such as railway inspection and unmanned aerial vehicle telemetering, a high-reliability large-aperture lens needs to be carried in order to accurately identify a target. The rise of the long-distance detection scene makes the market demand for large-aperture lenses larger and larger. Therefore, a high-reliability large-aperture infrared collimating lens is needed.

Disclosure of Invention

The application aims to provide a large-aperture infrared collimating lens which is used for solving the problems that the reliability is high in the current market, and the large-aperture infrared collimating lens is applied to a laser radar using C-band (1530nm-1565 nm) laser.

In a first aspect, the present application provides a large aperture infrared collimator lens, sequentially including, from an object side to an image side along an optical axis:

A first lens having positive optical power; a second lens having positive optical power; a third lens having negative optical power; a fourth lens having positive optical power; a fifth lens having negative optical power; a sixth lens having positive optical power; a seventh lens having negative optical power; wherein an object side of the fifth lens element is cemented with an image side of the fourth lens element, and an object side of the seventh lens element is cemented with an image side of the sixth lens element;

the total effective focal length of the large-aperture infrared collimating lens is f, the entrance pupil diameter of the large-aperture infrared collimating lens is EPD, and the large-aperture infrared collimating lens meets the following conditions: 1.0< f/EPD <1.5.

The large-aperture infrared collimating lens has good collimating effect and high reliability, is suitable for a laser radar using C-band (1530nm-1565 nm) laser, and meets the requirement of long-distance detection of a scene.

In an embodiment of the application, an object side surface of the third lens element is glued to an image side surface of the second lens element.

In the application, the arrangement can improve the assemblability of the lens.

In an embodiment of the application, the object-side surface of the first lens element is a convex surface, and the image-side surface of the first lens element is a plane, a convex surface or a concave surface; the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a convex surface or a concave surface; the object side surface of the third lens is a concave surface or a convex surface, and the image side surface of the third lens is a concave surface; the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a concave surface; the object side surface of the sixth lens is a convex surface, and the image side surface of the sixth lens is a concave surface; the seventh lens object-side surface is a convex surface, and the seventh lens image-side surface is a concave surface.

In an embodiment of the present application, an edge thickness of the first lens is ET1, a center thickness of the first lens on an optical axis is CT1, and the first lens satisfies: ET1/CT1>0.34.

According to the application, the edge of the first lens can be prevented from being broken during processing due to the fact that the edge of the first lens is too thin, and the manufacturability of the first lens is effectively improved.

In an embodiment of the present application, an edge thickness of the second lens is ET2, a center thickness of the second lens on an optical axis is CT2, an edge thickness of the third lens is ET3, a center thickness of the third lens on the optical axis is CT3, and the second lens and the third lens satisfy: 1.0< (CT2+CT3)/(ET 2+ET 3) < 1.5.

In the application, the arrangement is beneficial to correcting chromatic aberration of the large-aperture infrared collimating lens and improving manufacturability of the second lens and the third lens.

In an embodiment of the present application, an edge thickness of the fourth lens is ET4, a center thickness of the fourth lens on an optical axis is CT4, an edge thickness of the fifth lens is ET5, a center thickness of the fifth lens on the optical axis is CT5, and the fourth lens and the fifth lens satisfy: 1.0 < (CT4+CT5)/(ET 4+ET 5) < 1.5.

In the application, the arrangement is beneficial to correcting chromatic aberration of the large-aperture infrared collimating lens and improving manufacturability of the fourth lens and the fifth lens.

In an embodiment of the present application, a distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis is TD, a total effective focal length of the large-aperture infrared collimating lens is f, and the large-aperture infrared collimating lens satisfies: 1.5< TD/f <2.5.

According to the application, the length of the large-aperture infrared collimating lens can be prevented from being too large, and the larger focal section can be obtained while the caliber of the lens is reduced as much as possible, so that the lens performs better.

In an embodiment of the present application, a distance between an intersection point of the image side surface of the seventh lens element and the optical axis and a vertex of a maximum effective radius of the image side surface of the seventh lens element on the optical axis is SAG72, a distance between the image side surface of the seventh lens element and the image plane of the large-aperture infrared collimating lens element on the optical axis is BFL, and the large-aperture infrared collimating lens element satisfies: 0.1< SAG72/BFL < 0.3.

According to the application, the arrangement can enable the edge of the large-aperture infrared collimating lens to obtain higher brightness, and meanwhile, a sufficient optimal collimating adjustment space can be ensured.

In an embodiment of the present application, a distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis is TD, a sum of air intervals between any two adjacent lens elements on the optical axis is Σat, and the large-aperture infrared collimating lens satisfies: 1.0 < TD/ΣAT < 1.5.

In the application, the arrangement can ensure the processing and assembling characteristics, and avoid the problems of interference between front and rear lenses, great difficulty in forming the lens due to over-thin lens, easy deformation in assembling and the like caused by over-small gap.

In an embodiment of the present application, when a maximum collimation light spot of the large aperture infrared collimation lens is 100 mm, a maximum included angle between a principal ray of all fields of view of the large aperture infrared collimation lens and an image surface normal is ANG0, a minimum included angle between an upper ray of all fields of view of the large aperture infrared collimation lens and the image surface normal is ANG1, a minimum included angle between a lower ray of all fields of view of the large aperture infrared collimation lens and the image surface normal is ANG1, and the large aperture infrared collimation lens satisfies: ANG0<1.5 °, ANG1>22 °, ANG2>23 °.

In the application, the arrangement can ensure that the large-aperture infrared collimating lens can maximally emit collimating light spots with the diameter of 100 mm, and is suitable for long-distance detection of a laser radar.

One or more embodiments of the above-described solution may have the following advantages or benefits compared to the prior art:

By applying the large-aperture infrared collimating lens provided by the embodiment of the invention, the incident light is converged through the first lens, so that the light can be smoothly transmitted to the rear lens; the object side surface of the fifth lens is glued with the image side surface of the fourth lens, the object side surface of the seventh lens is glued with the image side surface of the sixth lens, the assembly performance of the lens is improved while the chromatic aberration of the optical system is corrected, the tolerance is introduced as little as possible, and the tolerance sensitivity of the whole lens is reduced; the second lens and the third lens also have chromatic aberration correcting functions. The invention can lead the lens to collimate the laser with large numerical aperture, obtain better collimation effect, is suitable for the laser radar using C wave band (1530nm-1565 nm) laser and meets the requirement of long-distance detection of scenes. The lens may be installed in a transmitting and receiving system of a laser radar to transmit and receive infrared laser light.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention, without limitation to the invention. In the drawings:

Fig. 1 is a schematic view showing a lens structure of a large-aperture infrared collimating lens according to an embodiment of the application.

Fig. 2 is a schematic diagram showing the diffraction ring-in energy curve of the lens structure shown in fig. 1.

Fig. 3 shows a schematic view of a dot column of the structural lens shown in fig. 1.

Fig. 4 is a schematic diagram showing a two-lens structure of a large-aperture infrared collimating lens according to an embodiment of the application.

Fig. 5 is a schematic diagram showing diffraction ring-in energy curves of the lens structure shown in fig. 4.

Fig. 6 shows a schematic view of a dot column of the structure lens shown in fig. 4.

Fig. 7 is a schematic diagram of a three-lens structure of a large-aperture infrared collimating lens according to an embodiment of the application.

Fig. 8 is a schematic diagram showing diffraction ring-in energy curves of the lens structure shown in fig. 7.

Fig. 9 shows a schematic view of a dot column of the structural lens of fig. 7.

Fig. 10 is a schematic diagram of a four-lens structure of a large-aperture infrared collimating lens according to an embodiment of the application.

FIG. 11 is a graph showing the diffraction ring-in energy curve of the lens structure of FIG. 10.

Fig. 12 shows a schematic view of a dot column of the structural lens of fig. 10.

Fig. 13 is a schematic diagram of a five-lens structure of a large-aperture infrared collimating lens according to an embodiment of the application.

Fig. 14 is a schematic view showing the diffraction ring-in energy curve of the lens structure shown in fig. 13.

Fig. 15 shows a schematic view of a dot column of the structural lens of fig. 13.

Fig. 16 shows a light path diagram of light rays striking an image surface from each field of view of the large-aperture infrared collimator according to the embodiment of the present application.

Detailed Description

The following will describe embodiments of the present invention in detail with reference to the drawings and examples, thereby solving the technical problems by applying technical means to the present invention, and realizing the technical effects can be fully understood and implemented accordingly. It should be noted that, as long as no conflict is formed, each embodiment of the present invention and each feature of each embodiment may be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

It should be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.

The embodiment of the application provides a large-aperture infrared collimating lens, which is used for solving the problems that the reliability is high in the current market, and the large-aperture infrared collimating lens is applied to a laser radar using C-band (1530nm-1565 nm) laser.

The principle and implementation of the large aperture infrared collimating lens of the present embodiment will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can understand the large aperture infrared collimating lens of the present embodiment without creative labor.

Referring to fig. 1, the present embodiment provides a large aperture infrared collimating lens, which includes seven lens groups including lenses having optical power, and is sequentially disposed from an object side to an image side along an optical axis: a first lens having positive optical power; a second lens having positive optical power; a third lens having negative optical power; a fourth lens having positive optical power; a fifth lens having negative optical power; a sixth lens having positive optical power; a seventh lens having negative optical power; wherein the object side of the fifth lens element is cemented with the image side of the fourth lens element, and the object side of the seventh lens element is cemented with the image side of the sixth lens element. The design wavelength range of the large-aperture infrared collimating lens is 1528 nm-1568 nm, and all lenses are glass spheres.

The large-aperture infrared collimating lens of the embodiment also needs to satisfy 1.0< f/EPD <1.5, where f represents the total effective focal length of the large-aperture infrared collimating lens, and EPD represents the entrance pupil diameter of the large-aperture infrared collimating lens. The arrangement can enable the large-aperture infrared collimating lens to collimate laser with large numerical aperture, and can obtain good collimating effect.

The large-aperture infrared collimating lens adopts reverse design, namely, the actual light is emitted by a laser radar on the image plane side, is collimated into parallel light beams by the lens, and then is emitted from the object plane side. The light reflected back after striking the object is still received by this lens and then returned to the lidar. The large-aperture infrared collimating lens of the embodiment is a lens capable of emitting laser light and receiving laser light.

The object side surface of the first lens element may be convex, and the image side surface of the first lens element may be planar, convex or concave. That is, the first lens may be provided as a biconvex lens having positive optical power, may be provided as a convex-concave lens having positive optical power, and may be provided as a convex-flat lens having positive optical power. The primary function of the first lens is to absorb light, and to collect incident light, so that light can be smoothly transmitted to the rear lens. Further, in order to prevent edge collapse caused by over-thinning of the first lens and effectively improve manufacturability of the first lens, the present embodiment further designs the first lens to satisfy ET1/CT1>0.34, where ET1 is an edge thickness of the first lens and CT1 is a center thickness of the first lens on an optical axis.

The object-side surface of the second lens element may be convex, and the image-side surface of the second lens element may be convex or concave. That is, the second lens may be provided as a biconvex lens having positive optical power, or may be provided as a convex-concave lens having positive optical power. The object-side surface of the third lens element may be concave or convex, and the image-side surface may be concave. That is, the third lens may be provided as a biconcave lens having negative optical power, or may be provided as a convex-concave lens having negative optical power. The large aperture infrared collimating lens of the present embodiment should be designed as a large aperture, small image plane lens, and the assembly tolerance is a major consideration, especially the component inclination tolerance, because the component slightly inclines light rays will deviate from the image plane greatly. Therefore, in order to reduce tolerance sensitivity of the entire lens to minimize the introduction of tolerance, the second lens element and the third lens element may preferably be arranged in a cemented state, i.e., the object-side surface of the third lens element is cemented with the image-side surface of the second lens element, so as to enhance assemblability of the large-aperture infrared collimator lens. The second lens and the third lens are mainly used for correcting chromatic aberration of the large-aperture infrared collimating lens.

Further, in order to facilitate correction of chromatic aberration of the large-aperture infrared collimating lens, manufacturability of the second lens and the third lens is further improved, and the second lens and the third lens are further designed to satisfy: 1.0< (CT2+CT3)/(ET 2+ET 3) < 1.5, wherein ET2 is the edge thickness of the second lens, CT2 is the center thickness of the second lens on the optical axis, ET3 is the edge thickness of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

The object-side surface of the fourth lens element may be convex, and the image-side surface of the fourth lens element may be concave. I.e. the fourth lens may be provided as a convex-concave lens having positive optical power. The object-side surface of the fifth lens element may be convex, and the image-side surface of the fifth lens element may be concave. I.e. the fifth lens may be provided as a convex-concave lens having a negative optical power. In order to reduce the tolerance sensitivity of the whole lens and minimize the introduced tolerance, the fourth lens element and the fifth lens element should be placed in a cemented state, i.e. the object-side surface of the fifth lens element is cemented with the image-side surface of the fourth lens element, so as to improve the assemblability of the large-aperture infrared collimator lens. The fourth lens and the fifth lens are mainly used for correcting chromatic aberration of the large-aperture infrared collimating lens.

Further, in order to facilitate correction of chromatic aberration of the large-aperture infrared collimating lens, manufacturability of the fourth lens and the fifth lens is further improved, and the fourth lens and the fifth lens are further designed to satisfy: 1.0 < (CT4+CT5)/(ET 4+ET 5) < 1.5, wherein ET4 is the edge thickness of the fourth lens, CT4 is the center thickness of the fourth lens on the optical axis, ET5 is the edge thickness of the fifth lens, and CT5 is the center thickness of the fifth lens on the optical axis.

The object-side surface of the sixth lens element may be convex, and the image-side surface of the sixth lens element may be concave. I.e. the sixth lens may be provided as a convex-concave lens having positive optical power. The object-side surface of the seventh lens element may be convex, and the image-side surface may be concave. That is, the seventh lens may be provided as a convex-concave lens having negative optical power. In order to reduce tolerance sensitivity of the whole lens and minimize the introduced tolerance, the sixth lens element and the seventh lens element should be placed in a cemented state, i.e. the object-side surface of the seventh lens element is cemented with the image-side surface of the sixth lens element, so as to improve assemblability of the large-aperture infrared collimator lens. The sixth lens and the seventh lens are mainly used for correcting chromatic aberration of the large-aperture infrared collimating lens.

Preferably, all lenses of the large-aperture infrared collimating lens of the embodiment have a caliber trend of the lens which is generally high and low on the left (i.e. high on the object side and low on the image side along the optical axis direction), so that the lens is easy to make structural members, and the lens barrel can also adopt a simple and convenient 'one-head' mode.

Further, the embodiment can also design the large-aperture infrared collimating lens to meet the following conditions: 1.5< TD/f <2.5, wherein TD is the distance between the object side surface of the first lens and the image side surface of the seventh lens on the optical axis, and f is the total effective focal length of the large-aperture infrared collimating lens. The arrangement can avoid the overlarge length of the large-aperture infrared collimating lens on one hand, and can obtain a larger focal section while reducing the caliber of the large-aperture infrared collimating lens as much as possible on the other hand, so that the large-aperture infrared collimating lens is better in performance.

The embodiment can also design a large-aperture infrared collimating lens to meet the following conditions: 0.1< SAG72/BFL < 0.3, wherein SAG72 is the distance between the intersection point of the seventh lens image side surface and the optical axis and the maximum effective radius vertex of the seventh lens image side surface on the optical axis, and BFL is the distance between the seventh lens image side surface and the image surface of the large-aperture infrared collimating lens on the optical axis. The arrangement can ensure that the edge of the large-aperture infrared collimating lens obtains higher brightness, and can ensure sufficient optimal collimating adjustment space.

The embodiment can also design a large-aperture infrared collimating lens to meet the following conditions: 1.0 < TD/ΣAT < 1.5, wherein TD is the distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis, and ΣAT is the sum of the air intervals between any two adjacent lens elements of the first lens element and the seventh lens element on the optical axis. The arrangement can ensure the processing and assembling characteristics, and avoid the problems of interference of front and rear lenses, high difficulty in forming the lens due to too thin lens, easy deformation in assembling and the like caused by too small gap.

The large-aperture infrared collimating lens of the embodiment can be designed to different maximum collimating light spots based on actual demands, for example, the large-aperture infrared collimating lens of the embodiment can be designed to have the maximum collimating light spot of 100 mm, and the design is suitable for laser radar long-distance detection. In fig. 16, there is an optical path (when light is actually emitted from the lidar, the principal ray is perpendicular to the image plane, and the upper and lower light rays are symmetrically distributed with respect to the principal ray.) with reference to fig. 16, for the design of the maximum collimation light spot, the incident light ray of the large aperture infrared collimation lens of this embodiment needs to satisfy: ANG0<1.5 °, ANG1>22 °, ANG2>23 °, wherein ANG0 is the maximum included angle between the principal ray of all fields of view of the large aperture infrared collimator lens and the normal line of the image plane, ANG1 is the minimum included angle between the upper ray of all fields of view of the large aperture infrared collimator lens and the normal line of the image plane, and ANG1 is the minimum included angle between the lower ray of all fields of view of the large aperture infrared collimator lens and the normal line of the image plane. The incident light rays of the large-aperture infrared collimating lens which do not meet the conditions cannot output corresponding light rays.

According to the large-aperture infrared collimating lens, the focal power and the surface type of each lens are reasonably distributed, so that the collimating capability of the lens can be effectively improved, a good collimating effect is achieved, the tolerance sensitivity of a lens system is reduced, and the whole lens is easier to process and manufacture.

It will be appreciated by those skilled in the art that the number of lenses making up the large aperture infrared collimator may be varied to achieve the various results and advantages described in this specification without departing from the technical solutions claimed herein. For example, although seven lenses are described as an example in the embodiment, the large-aperture infrared collimator lens is not limited to include seven lenses, but may include other numbers of lenses if necessary.

The main basis of the current evaluation of the lens performance is diffraction ring energy of an image plane, and a point list chart is used as an auxiliary reference. The diffraction circle energy refers to that a light spot is formed when light rays corresponding to a field of view are converged on an image surface, a circle is drawn by taking the mass center of the light spot as a circle center, the abscissa is a radius, the ordinate is the percentage of energy in the circle, and the more the percentage of energy in the circle in a certain radius range, the higher the performance of the lens is. The spot diagram shows the spot shape of the light rays of the corresponding field of view on the image surface, and the smaller the size of the spot diagram is, the better the performance of the surface lens is.

Five specific design examples suitable for the large aperture infrared collimator of the above embodiment are further described below with reference to the above-mentioned class diagrams.

Description of the preferred embodiment

Fig. 1 is a schematic view showing a lens structure of a large-aperture infrared collimating lens according to an embodiment of the application. The large aperture infrared collimating lens sequentially comprises from an object side to an image side along an optical axis: a first lens L1, a second lens L2, a third lens L3, a stop STO, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, a cover glass G8, and an imaging plane IMA.

The first lens element L1 has positive refractive power, wherein an object-side surface S1 thereof is convex, and an image-side surface S2 thereof is planar;

The second lens element L2 has positive refractive power, wherein an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is convex;

the third lens element L3 has negative refractive power, wherein an object-side surface S4 thereof is concave, and an image-side surface S5 thereof is concave;

the fourth lens element L4 has positive refractive power, wherein an object-side surface S6 thereof is convex, and an image-side surface S7 thereof is concave;

the fifth lens element L5 has negative refractive power, wherein an object-side surface S7 thereof is convex, and an image-side surface S8 thereof is concave;

the sixth lens element L6 with positive refractive power has a convex object-side surface S9 and a concave image-side surface S10;

the seventh lens element L7 with negative focal power has a convex object-side surface S10 and a concave image-side surface S11;

the cover glass G8 has an object side surface S12 and an image side surface S13 for protecting the light exit of the lidar, and incident light sequentially passes through each of the surfaces S1 to S13 and is finally imaged on the imaging surface IMA. Where OBJ represents the object plane.

F/EPD = 1.217, where f is the total effective focal length of the large aperture infrared collimator lens and EPD is the entrance pupil diameter of the large aperture infrared collimator lens.

As shown in table 1, the basic parameters of the large aperture infrared collimator lens of the first embodiment are shown in table 1, wherein the unit of the radius of curvature, thickness and total effective focal length is millimeter (mm).

TABLE 1

The principal value parameters in specific example one are as follows: the total length/mm of the system is 283.874, the image space F/# is 1.217, the total effective focal length F/mm is 124.627, the half FOV/° is 1.55, the entrance pupil diameter/mm is 102, the image space NA is 0.38, and the image space is 3.372.

The large aperture infrared collimating lens in the specific example one satisfies:

ET1/CT1 = 0.492, where ET1 is the edge thickness of the first lens and CT1 is the center thickness of the first lens on the optical axis.

(CT 2+ct 3)/(ET 2+et3) = 1.142, where ET2 is the edge thickness of the second lens, CT2 is the center thickness of the second lens on the optical axis, ET3 is the edge thickness of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

(CT 4+ct 5)/(ET 4+et5) =1.164, where ET4 is the edge thickness of the fourth lens, CT4 is the center thickness of the fourth lens on the optical axis, ET5 is the edge thickness of the fifth lens, and CT5 is the center thickness of the fifth lens on the optical axis.

TD/f=2.048, where the distance between the object side surface of the TD first lens and the image side surface of the seventh lens on the optical axis, f is the total effective focal length of the large aperture infrared collimating lens.

SAG 72/bfl=0.247, where SAG72 is the distance on the optical axis between the intersection of the seventh lens image side and the optical axis and the maximum effective radius vertex of the seventh lens image side, and BFL is the distance on the optical axis between the seventh lens image side and the image plane of the large aperture infrared collimator lens.

TD/Σat=1.434, where TD is the distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis, Σat is the sum of the air intervals between any two adjacent lens elements on the optical axis.

FIG. 2 is a graph showing the diffraction ring-in energy curve of the lens structure of FIG. 1; FIG. 3 shows a schematic diagram of a dot column of the structural lens of FIG. 1; referring to fig. 2 and 3, the large aperture infrared collimating lens of the first embodiment can collimate laser light with a large numerical aperture, and obtain a good collimation effect.

Specific examples II

Fig. 4 is a schematic diagram showing a two-lens structure of a large-aperture infrared collimating lens according to an embodiment of the application. Compared with the first embodiment, the F number of the second embodiment is larger, i.e. 1.48, and the F number of the first embodiment is smaller, i.e. 1.22, and in addition, there are some main value parameters, such as height and total effective focal length, the image height of the second embodiment is 4.1mm, the total effective focal length is 151.5mm, the image height of the first embodiment is 3.4mm, and the total effective focal length is 124.6mm. Other arrangements (e.g. the large aperture infrared collimator lens includes lenses sequentially from the object side to the image side along the optical axis, the design structures of the object plane and the side of each lens, etc.) are not very different from those of the specific example.

In this embodiment, f/EPD = 1.48, where f is the total effective focal length of the large aperture infrared collimator lens and EPD is the entrance pupil diameter of the large aperture infrared collimator lens.

As shown in table 2, the basic parameters of the large aperture infrared collimator lens of the second specific example are shown in the table, wherein the unit of the curvature radius, thickness and total effective focal length is millimeter (mm).

TABLE 2

The principal value parameters in concrete example two are as follows: the total length/mm of the system is 296.785, the image space F/# is 1.48, the total effective focal length F/mm is 151.522, the half FOV/° is 1.55, the entrance pupil diameter/mm is 102.38, the image space NA is 0.3, and the image space is 4.104.

The large-aperture infrared collimating lens in the specific example II meets the following conditions:

ET1/CT1 = 0.523, where ET1 is the edge thickness of the first lens and CT1 is the center thickness of the first lens on the optical axis.

(CT 2+ CT 3)/(ET 2+ ET 3) =1.102, wherein ET2 is the edge thickness of the second lens, CT2 is the center thickness of the second lens on the optical axis, ET3 is the edge thickness of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

(CT 4+ct 5)/(ET 4+et5) =1.167, where ET4 is the edge thickness of the fourth lens, CT4 is the center thickness of the fourth lens on the optical axis, ET5 is the edge thickness of the fifth lens, and CT5 is the center thickness of the fifth lens on the optical axis.

TD/f= 1.722, where the distance between the object side surface of the TD first lens and the image side surface of the seventh lens on the optical axis, the total effective focal length of the f-large aperture infrared collimating lens.

SAG 72/bfl=0.204, where SAG72 is the distance on the optical axis between the intersection of the seventh lens image side and the optical axis and the vertex of the maximum effective radius of the seventh lens image side, and BFL is the distance on the optical axis between the seventh lens image side and the image plane of the large aperture infrared collimator.

TD/Σat=1.457, where TD is the distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis, and Σat is the sum of the air intervals between any two adjacent lens elements on the optical axis.

FIG. 5 is a graph showing the diffraction ring-in energy curve of the lens structure of FIG. 4; FIG. 6 shows a schematic diagram of a dot column of the structural lens of FIG. 4; referring to fig. 5 and 6, the large aperture infrared collimating lens of the second embodiment can collimate the laser light with a large numerical aperture, and obtain a better collimation effect.

Description of the preferred embodiment

Fig. 7 is a schematic diagram of a three-lens structure of a large-aperture infrared collimating lens according to an embodiment of the present application. In comparison with the first embodiment, the third embodiment changes the shape of some lenses, so that it can be demonstrated that the change of the shape of some lenses does not affect the specific function of the lens. Specifically, the object side surface of the first lens is changed from the plane of the first specific example to the convex surface. Other arrangements (e.g. the large aperture infrared collimator lens includes lenses sequentially from the object side to the image side along the optical axis, the design structures of the object plane and the side of each lens, etc.) are not very different from those of the specific example.

In this embodiment, f/EPD = 1.217, where f is the total effective focal length of the large aperture infrared collimator lens and EPD is the entrance pupil diameter of the large aperture infrared collimator lens.

As shown in table 3, the basic parameters of the large aperture infrared collimator lens of the third example are shown in table 3, wherein the unit of the radius of curvature, thickness, and total effective focal length is millimeter (mm).

TABLE 3 Table 3

The principal value parameters in the specific example three are as follows: the total length/mm of the system is 300, the image space F/# is 1.2173, the total effective focal length F/mm is 124.627, the half FOV/° is 1.55, the entrance pupil diameter/mm is 102.38, the image space NA is 0.38, and the image space is 3.37.

The large-aperture infrared collimating lens in the third specific example satisfies the following conditions:

ET1/CT1 = 0.499, where ET1 is the edge thickness of the first lens and CT1 is the center thickness of the first lens on the optical axis.

(CT 2+ CT 3)/(ET 2+ ET 3) =1.169, wherein ET2 is the edge thickness of the second lens, CT2 is the center thickness of the second lens on the optical axis, ET3 is the edge thickness of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

(CT 4+ct 5)/(ET 4+et5) =1.24, wherein ET4 is the edge thickness of the fourth lens, CT4 is the center thickness of the fourth lens on the optical axis, ET5 is the edge thickness of the fifth lens, and CT5 is the center thickness of the fifth lens on the optical axis.

TD/f= 2.176, where the distance between the object side surface of the TD first lens and the image side surface of the seventh lens on the optical axis, the total effective focal length of the f-large aperture infrared collimating lens.

SAG 72/bfl=0.255, where SAG72 is the distance on the optical axis between the intersection of the seventh lens image side and the optical axis and the vertex of the maximum effective radius of the seventh lens image side, and BFL is the distance on the optical axis between the seventh lens image side and the image plane of the large aperture infrared collimator lens.

TD/Σat=1.334, where TD is the distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis, Σat is the sum of the air intervals between any two adjacent lens elements on the optical axis.

FIG. 8 is a graph showing the diffraction ring-in energy curve of the lens structure of FIG. 7; FIG. 9 is a schematic view of a point column for the structural lens of FIG. 7; referring to fig. 8 and 9, the large aperture infrared collimating lens of the third embodiment can collimate laser light with a large numerical aperture, and obtain a good collimation effect.

Description of the preferred embodiment

Fig. 10 is a schematic diagram of a four-lens structure of a large-aperture infrared collimating lens according to an embodiment of the present application. The F number of the fourth example is 1.12, and the F number of the first example is 1.22 more than that of the first example. In addition, there are some principal parameters, such as image height and total effective focal length, in which the image height of the fourth example is 3.0mm, the total effective focal length is 110.6mm, the image height of the first example is 3.4mm, and the total effective focal length is 124.6mm. Other arrangements (e.g. the large aperture infrared collimator lens includes lenses sequentially from the object side to the image side along the optical axis, the design structures of the object plane and the side of each lens, etc.) are not very different from those of the specific example.

In this embodiment, f/EPD = 1.08, where f is the total effective focal length of the large aperture infrared collimator lens and EPD is the entrance pupil diameter of the large aperture infrared collimator lens.

As shown in table 4, a basic parameter table of a large aperture infrared collimator lens of a specific example four, in which the unit of radius of curvature, thickness, and total effective focal length is millimeter (mm).

TABLE 4 Table 4

The principal value parameters in the specific example four are as follows: the total length/mm of the system is 300, the image space F/# is 1.122, the total effective focal length F/mm is 110.57, the half FOV/° is 1.55, the entrance pupil diameter/mm is 102.38, the image space high IMH/mm is 2.985, and the image space NA is 0.42.

The large-aperture infrared collimating lens in the specific example IV satisfies the following conditions:

ET1/CT1 = 0.69, where ET1 is the edge thickness of the first lens and CT1 is the center thickness of the first lens on the optical axis.

(CT 2+ct 3)/(ET 2+et3) = 1.208, where ET2 is the edge thickness of the second lens, CT2 is the center thickness of the second lens on the optical axis, ET3 is the edge thickness of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

(CT 4+ct 5)/(ET 4+et5) =1.263, where ET4 is the edge thickness of the fourth lens, CT4 is the center thickness of the fourth lens on the optical axis, ET5 is the edge thickness of the fifth lens, and CT5 is the center thickness of the fifth lens on the optical axis.

TD/f=2.464, where the distance between the object side surface of the TD first lens and the image side surface of the seventh lens on the optical axis, f is the total effective focal length of the large aperture infrared collimating lens.

SAG 72/bfl=0.2, where SAG72 is the distance on the optical axis between the intersection of the seventh lens image side and the optical axis and the vertex of the maximum effective radius of the seventh lens image side, and BFL is the distance on the optical axis between the seventh lens image side and the image plane of the large aperture infrared collimator lens.

TD/Σat=1.387, where TD is the distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis, Σat is the sum of the air intervals between any two adjacent lens elements on the optical axis.

FIG. 11 is a graph showing the diffraction ring-in energy curve of the lens structure of FIG. 10; FIG. 12 is a schematic view of a point column for the structural lens of FIG. 7; referring to fig. 11 and 12, the large aperture infrared collimator lens of the fourth embodiment can collimate laser light with a large numerical aperture, and obtain a good collimation effect.

Description of the preferred embodiment

Fig. 13 is a schematic diagram of a five-lens structure of a large-aperture infrared collimating lens according to an embodiment of the present application. Compared with the first specific example, the second lens and the third lens in the fifth example are not glued together, and the fact that the second lens and the third lens can be used normally under the condition that the second lens and the third lens are not glued is proved, and the specific function of the lens is not affected. Since the second lens and the third lens are not glued, the surface S4 is no longer shared, and the individual lens cases are:

the third lens element L3 has negative refractive power, wherein an object-side surface S5 thereof is concave, and an image-side surface S6 thereof is concave;

The fourth lens element L4 has positive refractive power, wherein an object-side surface S7 thereof is convex, and an image-side surface S8 thereof is concave;

The fifth lens element L5 has negative refractive power, wherein an object-side surface S8 thereof is convex, and an image-side surface S9 thereof is concave;

the sixth lens element L6 with positive refractive power has a convex object-side surface S10 and a concave image-side surface S11;

the seventh lens element L7 with negative focal power has a convex object-side surface S11 and a concave image-side surface S12;

the cover glass G8 has an object side surface S13 and an image side surface S14 for protecting the light exit of the lidar, and incident light sequentially passes through each of the surfaces S1 to S14 and is finally imaged on the imaging surface IMA. Where OBJ represents the object plane.

In this embodiment, f/EPD = 1.22, where f is the total effective focal length of the large aperture infrared collimator lens and EPD is the entrance pupil diameter of the large aperture infrared collimator lens.

As shown in table 5, the basic parameters of the large aperture infrared collimator of the fifth embodiment are shown in table 5, wherein the unit of the radius of curvature, thickness and total effective focal length is millimeter (mm).

TABLE 5

The principal value parameters in concrete example five are as follows: the total length/mm of the system is 296.871, the image space F/# is 1.2173, the total effective focal length F/mm is 124.627, the half FOV/° is 1.55, the entrance pupil diameter/mm is 102.38, the image space NA is 0.38, and the image space is 3.362.

The large-aperture infrared collimating lens in the fifth specific example satisfies the following conditions:

ET1/CT1 = 0.346, where ET1 is the edge thickness of the first lens and CT1 is the center thickness of the first lens on the optical axis.

(CT 2+ CT 3)/(ET 2+ ET 3) =1.047, wherein ET2 is the edge thickness of the second lens, CT2 is the center thickness of the second lens on the optical axis, ET3 is the edge thickness of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

(CT 4+ct 5)/(ET 4+et5) =1.177, wherein ET4 is the edge thickness of the fourth lens, CT4 is the center thickness of the fourth lens on the optical axis, ET5 is the edge thickness of the fifth lens, and CT5 is the center thickness of the fifth lens on the optical axis.

TD/f=2.17, where the distance between the object side surface of the TD first lens and the image side surface of the seventh lens on the optical axis, f is the total effective focal length of the large aperture infrared collimating lens.

SAG 72/bfl=0.147, where SAG72 is the distance on the optical axis between the intersection of the seventh lens image side and the optical axis and the vertex of the maximum effective radius of the seventh lens image side, and BFL is the distance on the optical axis between the seventh lens image side and the image plane of the large aperture infrared collimating lens.

TD/Σat=1.366, where TD is the distance between the object side surface of the first lens element and the image side surface of the seventh lens element on the optical axis, and Σat is the sum of the air intervals between any two adjacent lens elements on the optical axis.

FIG. 14 is a graph showing the diffraction ring-in energy curve of the lens structure of FIG. 13; FIG. 15 is a schematic view of a point column of the structured lens of FIG. 13; referring to fig. 14 and 15, the large aperture infrared collimator lens of the fifth embodiment can collimate laser light with a large numerical aperture, and obtain a good collimation effect.

According to the large-aperture infrared collimating lens provided by the embodiment of the invention, the incident light is converged through the first lens, so that the light can be smoothly transmitted to the rear lens; the object side surface of the fifth lens is glued with the image side surface of the fourth lens, the object side surface of the seventh lens is glued with the image side surface of the sixth lens, the assembly performance of the lens is improved while the chromatic aberration of the optical system is corrected, the tolerance is introduced as little as possible, and the tolerance sensitivity of the whole lens is reduced; the second lens and the third lens also have chromatic aberration correcting functions. The invention can lead the lens to collimate the laser with large numerical aperture, obtain better collimation effect, is suitable for the laser radar using C wave band (1530nm-1565 nm) laser and meets the requirement of long-distance detection of scenes. The lens may be installed in a transmitting and receiving system of a laser radar to transmit and receive infrared laser light.

The descriptions of the processes or structures corresponding to the drawings have emphasis, and the descriptions of other processes or structures may be referred to for the parts of a certain process or structure that are not described in detail.

The above embodiments are merely illustrative of the principles of the present application and its effectiveness, and are not intended to limit the application. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the application. Accordingly, it is intended that all equivalent modifications and variations of the application be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. The utility model provides a big aperture infrared collimating lens which characterized in that includes in proper order along the optical axis from object side to image side:

2. The large aperture infrared collimating lens of claim 1, wherein an object side of the third lens is cemented with an image side of the second lens.

3. The large aperture infrared collimator lens of claim 1, wherein the first lens object-side surface is convex, and the first lens image-side surface is planar, convex or concave; the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a convex surface or a concave surface; the object side surface of the third lens is a concave surface or a convex surface, and the image side surface of the third lens is a concave surface; the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a concave surface; the object side surface of the sixth lens is a convex surface, and the image side surface of the sixth lens is a concave surface; the seventh lens object-side surface is a convex surface, and the seventh lens image-side surface is a concave surface.

4. The large aperture infrared collimator lens of claim 1, wherein an edge thickness of the first lens is ET1, a center thickness of the first lens on an optical axis is CT1, and the first lens satisfies: ET1/CT1>0.34.

5. The large aperture infrared collimating lens of claim 1, wherein an edge thickness of the second lens is ET2, a center thickness of the second lens on an optical axis is CT2, an edge thickness of the third lens is ET3, a center thickness of the third lens on the optical axis is CT3, and the second lens and the third lens satisfy: 1.0< (CT2+CT3)/(ET 2+ET 3) < 1.5.

6. The large aperture infrared collimating lens of claim 1, wherein an edge thickness of the fourth lens is ET4, a center thickness of the fourth lens on an optical axis is CT4, an edge thickness of the fifth lens is ET5, a center thickness of the fifth lens on the optical axis is CT5, and the fourth lens and the fifth lens satisfy: 1.0 < (CT4+CT5)/(ET 4+ET 5) < 1.5.

7. The large aperture infrared collimator of claim 1, wherein the distance between the object side surface of the first lens and the image side surface of the seventh lens on the optical axis is TD, the total effective focal length of the large aperture infrared collimator is f, and the large aperture infrared collimator satisfies: 1.5< TD/f <2.5.

8. The large aperture infrared collimator of claim 1, wherein a distance between an intersection point of the seventh lens image side surface and the optical axis and a maximum effective radius vertex of the seventh lens image side surface on the optical axis is SAG72, a distance between the seventh lens image side surface and an image plane of the large aperture infrared collimator on the optical axis is BFL, and the large aperture infrared collimator satisfies: 0.1< SAG72/BFL < 0.3.

9. The large aperture infrared collimator lens of claim 1, wherein an optical axis distance between the object side surface of the first lens and the image side surface of the seventh lens is TD, a sum of air intervals between any two adjacent lenses in the first lens to the seventh lens on the optical axis is Σat, and the large aperture infrared collimator lens satisfies: 1.0 < TD/ΣAT < 1.5.

10. The large aperture infrared collimator lens of claim 1, wherein when the maximum collimation light spot of the large aperture infrared collimator lens is 100mm, the maximum included angle between the principal rays of all fields of view of the large aperture infrared collimator lens and the normal line of the image surface is ANG0, the minimum included angle between the upper rays of all fields of view of the large aperture infrared collimator lens and the normal line of the image surface is ANG1, the minimum included angle between the lower rays of all fields of view of the large aperture infrared collimator lens and the normal line of the image surface is ANG1, and the large aperture infrared collimator lens satisfies: ANG0<1.5 °, ANG1>22 °, ANG2>23 °.