CN109031587B

CN109031587B - Optical lens

Info

Publication number: CN109031587B
Application number: CN201710433514.XA
Authority: CN
Inventors: 张绍鹏; 徐超; 杨佳
Original assignee: Ningbo Sunny Automotive Optech Co Ltd
Current assignee: Ningbo Sunny Automotive Optech Co Ltd
Priority date: 2017-06-09
Filing date: 2017-06-09
Publication date: 2021-01-12
Anticipated expiration: 2037-06-09
Also published as: CN109031587A

Abstract

The invention provides an optical lens. The optical lens includes, in order from an object side to an image side: the first lens is a meniscus lens with positive focal power, and the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens is a meniscus lens with negative focal power, and the object side surface of the second lens is a convex surface and the image side surface of the second lens is a concave surface; the third lens is a meniscus lens with positive focal power, and the object side surface of the third lens is a concave surface and the image side surface of the third lens is a convex surface; and a fourth lens having a positive refractive power and a convex object-side surface. The optical lens provided by the invention can realize high light input quantity while keeping the miniaturization of the lens by optimally setting the shapes of the lenses and reasonably distributing the focal power of the lenses.

Description

Optical lens

Technical Field

The present invention relates to the field of optical lenses, and more particularly, to an optical lens capable of achieving a high light incident amount and small distortion while keeping the lens compact.

Background

The laser radar is a radar system that detects a characteristic amount such as a position and a velocity of a target by emitting a laser beam. In terms of working principle, like the microwave radar, the laser radar transmits a detection signal (laser beam) to a target, compares a received signal (target echo) reflected from the target with the transmission signal, and obtains relevant information of the target after appropriate processing, such as parameters of target distance, azimuth, height, speed, attitude, even shape and the like, so as to detect, track and identify the target.

The laser radar generally comprises a laser transmitter, an optical receiver, a rotary table, an information processing system and the like, wherein the laser transmitter converts electric pulses into optical pulses to be transmitted out, and the optical receiver restores the optical pulses reflected from a target into the electric pulses to be transmitted to a display to be displayed.

With the development of unmanned driving, lidar becomes an important device for realizing unmanned driving, and the lidar determines relevant information of an obstacle object, such as position, speed and the like, by analyzing received reflected laser. The optical lens is an important component of the laser radar, and as mentioned above, the optical lens is required to collimate the light beam at the transmitting end of the laser radar, and the optical lens is required to receive the light beam at the receiving end of the laser radar.

Therefore, the laser radar currently used in the market needs to be equipped with two types of lenses, one type is a transmitting-end lens, and the other type is a receiving-end lens.

Different from a common lens, a receiving end lens of the laser radar does not require imaging, but needs to collect reflected light as much as possible, so that a rear chip can receive most energy of the reflected light. Therefore, the lens at the receiving end of the laser radar requires a small FNO, so that the lens can receive more light, and the requirement on distortion is high.

Further, there is a need to keep the lens compact.

Accordingly, there is a need for improved optical lenses and lidar.

Disclosure of Invention

The present invention has been made to address the above-described drawbacks and deficiencies of the prior art, and it is an object of the present invention to provide a novel and improved optical lens and lidar capable of achieving a high amount of incident light and small distortion while keeping the lens compact.

An object of the present invention is to provide an optical lens and a laser radar that can realize a high light incident amount while keeping the lens compact by optimally setting the shapes of respective lenses and reasonably distributing the focal powers of the respective lenses.

An object of the present invention is to provide an optical lens and a laser radar, which can collect more light rays to enter an optical system by using a meniscus lens with a positive focal power as a first lens, thereby achieving a high light incident amount.

An object of the present invention is to provide an optical lens and a laser radar, which can effectively reduce the aperture of a second lens and the distance between the first lens and the second lens by adopting a meniscus shape for a first lens, and contribute to the miniaturization of the optical lens.

An object of the present invention is to provide an optical lens and a laser radar that can achieve smooth transition of light and reduce aberration generated by a first lens by the shape and power setting of a second lens.

An object of the present invention is to provide an optical lens and a laser radar that can further reduce aberrations generated by a first lens and a second lens and facilitate adjustment of an imaging size by the shape and power setting of a third lens.

An object of the present invention is to provide an optical lens and a laser radar, which are helpful to collect the emergent light from the third lens and converge the emergent light to a chip by the convex object side surface of the fourth lens.

An object of the present invention is to provide an optical lens and a laser radar that can effectively reduce the cost of the optical lens by setting the second lens and the third lens to have substantially the same aperture.

An object of the present invention is to provide an optical lens and a laser radar that can control the magnitude of a diffused spot and the magnitude of distortion to provide excellent optical performance by providing a second lens and a third lens as aspherical lenses.

An object of the present invention is to provide an optical lens and a laser radar that can achieve good thermal stability by providing a second lens and a third lens as glass aspherical lenses.

An object of the present invention is to provide an optical lens and a laser radar, which can cancel out a defocus change at the time of temperature change to improve thermal stability and realize a high light input amount with a small fluctuation range by providing a second lens and a third lens as plastic aspherical lenses having substantially the same material/outer shape.

An object of the present invention is to provide an optical lens and a laser radar capable of effectively correcting distortion and ensuring small distortion by providing a second lens and a third lens in a substantially symmetrical approximately concentric circular shape.

An object of the present invention is to provide an optical lens and a laser radar, which facilitate processing of lenses and realize low cost of the optical lens by providing a second lens and a third lens as plastic lenses having a shape close to a concentric circle.

An object of the present invention is to provide an optical lens and a laser radar capable of receiving more reflected light by providing a large diaphragm aperture.

An object of the present invention is to provide an optical lens and a laser radar that can make the energy entering the lens high, thereby achieving a high amount of incident light, and obtaining a large angle of view, by setting the focal lengths of the first lens and the fourth lens large, and setting the focal lengths of the second lens and the third lens small.

An object of the present invention is to provide an optical lens and a laser radar that contribute to achieving a smooth transition of light in the entire optical system by setting the refractive index and abbe number of the first lens to the fourth lens, thereby obtaining a high incident light amount and a large angle of view.

According to an aspect of the present invention, there is provided an optical lens including, in order from an object side to an image side: the first lens is a meniscus lens with positive focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens is a meniscus lens with negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; the third lens is a meniscus lens with positive focal power, the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; and a fourth lens having a positive refractive power, the object-side surface of the fourth lens being a convex surface. In the optical lens assembly, an image-side surface of the fourth lens element is a flat surface, or an image-side surface of the fourth lens element is a concave surface.

In the above optical lens, the second lens and the third lens have at least one aspheric lens.

In the above optical lens, the second lens and the third lens have shapes close to concentric circles.

In the above optical lens, the second lens and the third lens are plastic lenses.

In the above optical lens, further comprising: a large aperture stop located between the second lens and the third lens.

In the above optical lens, the first lens to the fourth lens satisfy the following conditional expression (1):

TTL/F≤1.6(1)

wherein F is the whole group focal length value of the optical lens, and TTL is the optical length of the optical lens.

In the above optical lens, focal lengths of the first lens to the fourth lens satisfy the following conditional expression (2):

F1/F≤1.6(2)

wherein F1 is the focal length of the first lens, and F is the entire set of focal length values of the optical lens.

In the above optical lens, focal lengths of the first lens to the fourth lens satisfy the following conditional expression (3):

i is not less than 4 (3) | F2/F

Wherein F2 is the focal length of the second lens, and F is the entire set of focal length values of the optical lens.

In the above optical lens, focal lengths of the first lens to the fourth lens satisfy the following conditional expression (4):

F3/F≥12 (4)

wherein F3 is the focal length of the third lens, and F is the entire set of focal length values of the optical lens.

In the above optical lens, focal lengths of the first lens to the fourth lens satisfy the following conditional expression (5):

F4/F≤1.4 (5)

wherein F4 is the focal length of the fourth lens, and F is the entire set of focal length values of the optical lens.

In the above optical lens, the second lens satisfies the following conditional expression (6):

0.5≤(R4+d3)/R3≤1.5 (6)

wherein R3 is a radius of curvature of an object-side surface of the second lens, R4 is a radius of curvature of an image-side surface of the second lens, and d3 is a thickness of the second lens.

In the above optical lens, the third lens satisfies the following conditional expression (7):

0.5 ≦ (R6 | + d 6)/R7 | ≦ 1.5 (7)

Wherein R6 is a radius of curvature of an object-side surface of the third lens, R7 is a radius of curvature of an image-side surface of the third lens, and d6 is a thickness of the third lens.

According to another aspect of the present invention, there is provided a laser radar including the above-described optical lens as a receiving-end lens.

The optical lens and the laser radar provided by the invention can realize high light input quantity while keeping the miniaturization of the lens by optimally setting the shapes of the lenses and reasonably distributing the focal power of the lenses.

Drawings

Fig. 1 illustrates a lens configuration of an optical lens according to a first embodiment of the present invention;

fig. 2 illustrates a lens configuration of an optical lens according to a second embodiment of the present invention;

FIG. 3 is a schematic block diagram of a lidar in accordance with an embodiment of the invention.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

The terms and words used in the following specification and claims are not limited to the literal meanings, but are used only by the inventors to enable a clear and consistent understanding of the invention. Accordingly, it will be apparent to those skilled in the art that the following descriptions of the various embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

The terminology used herein is for the purpose of describing various embodiments only and is not intended to be limiting. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, numbers, steps, operations, components, elements, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, elements, or groups thereof.

Terms used herein, including technical and scientific terms, have the same meaning as terms commonly understood by one of ordinary skill in the art, unless otherwise defined. It will be understood that terms defined in commonly used dictionaries have meanings that are consistent with their meanings in the prior art.

The invention is described in further detail below with reference to the following figures and detailed description:

[ arrangement of optical lens ]

According to an aspect of the embodiments of the present invention, there is provided an optical lens, in order from an object side to an image side, including: the first lens is a meniscus lens with positive focal power, and the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens is a meniscus lens with negative focal power, and the object side surface of the second lens is a convex surface and the image side surface of the second lens is a concave surface; the third lens is a meniscus lens with positive focal power, and the object side surface of the third lens is a concave surface and the image side surface of the third lens is a convex surface; and a fourth lens having a positive refractive power and a convex object-side surface.

In the optical lens according to the embodiment of the invention, the first lens adopts the meniscus lens with positive focal power, so that the incident angle of incident light on a head-on surface is small, the light in a field of view is collected as much as possible, more light is collected and enters an optical system, and high incident light quantity is realized, and the requirement of a receiving end lens of a laser radar is met. In addition, the first lens adopts a meniscus shape, so that the caliber of the second lens and the distance between the first lens and the second lens can be effectively reduced, and the optical lens is beneficial to realizing miniaturization.

Because the first lens of the optical lens is a convergent lens, the light trend is relatively gentle by utilizing the focal length setting of the second lens, so that the light is smoothly transited to the rear. Here, by setting the focal length of the second lens to be much larger than that of the first lens, the above gentle tendency of the light can be achieved, which will be described in detail below.

In addition, the third lens element is a meniscus lens element concave toward the object side, and has a concave object-side surface and a convex image-side surface. The third lens is a convergent lens, so that the divergent light rays passing through the second lens smoothly enter the rear part, and the aperture of the fourth lens is favorably reduced. And, by the shape and power setting of the third lens, it is advantageous to shorten the total length of the optical system. In the optical lens assembly, an image-side surface of the fourth lens element is a flat surface, or an image-side surface of the fourth lens element is a concave surface.

Preferably, in the above optical lens, the second lens and the third lens are aspherical lenses.

The second lens and the third lens are aspheric lenses, so that the optical performance is improved by controlling the size of the dispersed spot and the size of distortion. That is, the optical lens according to the embodiment of the present invention has a high Energy (circled Energy), that is, the size of the diffuse spot is strictly controlled, so that the diffuse spot is small, and thus the Energy of the light entering the optical system is maximally received by a single pixel. Here, the diffuse spot refers to a diffuse circular projection formed on an image plane, where an imaging beam cannot converge at one point due to aberration when an object point is imaged. Preferably, the circle-in energy of the optical lens according to the embodiment of the present invention reaches 95% or more, and the fluctuation range is stabilized to 5% or less in the case of temperature change.

In addition, according to the CRA of the optical lens disclosed by the embodiment of the invention, an included angle formed by the chief ray emitted from the last lens and the normal line of the image surface is small, so that the fluctuation of the dispersed spots can be ensured to be small under the condition of large depth of focus (DOF), and the dispersed spots under the large DOF are all in the size of a pixel. Here, the depth of focus refers to the imaging clarity range on both sides of the image plane of the lens.

In the above optical lens, the second lens and the third lens may be glass aspherical lenses. The lens thermal compensation is facilitated by the glass aspheric lens, but the cost is high. Also, when a glass aspherical lens having a high refractive index is employed, it may be further advantageous to reduce the volume of the optical lens in the radial direction.

Alternatively, the second lens and the third lens are plastic aspherical lenses. Thus, the manufacturing cost of the optical lens can be reduced by using the plastic aspherical lens. However, since the temperature performance of the plastic lens is poor, it is preferable that the materials/profiles of the second lens and the third lens are substantially identical, thereby contributing to an increase in thermal stability. Thus, the defocusing changes can be mutually offset when the temperature changes, for example, the fluctuation range of the circle-in energy of the optical lens according to the embodiment of the invention is below 5 percent in the range of-40 ℃ to 85 ℃.

Preferably, in the above optical lens, the second lens and the third lens have shapes close to concentric circles. More preferably, the second lens and the third lens have symmetrical concentric circular shapes. Thus, the optical lens according to the embodiment of the present invention can effectively correct distortion by using two concentric circular lenses, and ensure that the distortion is small, for example, within 1%.

And, the second lens and the third lens are preferably plastic lenses, thus facilitating the processing of the lenses and realizing low cost of the optical lens.

Preferably, in the above optical lens, a large diaphragm aperture is further included to facilitate realization of a small FNO. Thus, more reflected light rays can be received through a large diaphragm aperture, and thus, smooth transition of light rays in the whole optical lens needs to be realized. This is achieved by setting the focal length F of the first lens to the fourth lens, specifically, the first lens and the last lens need to be able to effectively converge the light angle, so the F of the first lens and the fourth lens is small, and the middle lens needs to achieve a smooth transition of light, so the F of the second lens and the third lens is large.

Preferably, the aperture stop is located between the second lens and the third lens, so as to facilitate effective beam-closing of light rays entering the optical system and reduce the aperture of a lens of the optical system. Of course, the skilled person will understand that the diaphragm may also be located between any other lenses.

More specifically, the second lens is a meniscus lens convex toward the object, has a large focal length F, and allows light to smoothly transition to the stop and then to the rear optical system, and the second lens can reduce aberration generated by the first lens, thereby performing the function of smoothly transitioning light. The third lens is a meniscus lens convex to the image side, which can further reduce aberration generated by the first lens and the second lens and help to adjust the imaging size. In addition, it is preferable that the calibers of the second lens and the third lens are made substantially the same to effectively reduce the cost.

Moreover, the object side surface of the fourth lens is a convex surface, which is helpful for collecting the light emitted from the L3 and converging the light on the chip, and the F of the fourth lens is also small.

Preferably, in the above optical lens, the first lens to the fourth lens satisfy the following conditional expression (1):

TTL/F≤1.6 (1)

where F is a focal length value of the entire group of the optical lens, and TTL is an optical length of the optical lens, that is, a distance from an outermost point of the object side of the first lens to the imaging focal plane.

In this way, by setting the powers and shapes of the first lens to the fourth lens, miniaturization of the optical lens can be achieved.

Preferably, in the above optical lens, the focal length F1 of the first lens, the focal length F2 of the second lens, the focal length F3 of the third lens, and the focal length F4 of the fourth lens satisfy the following conditional expressions (2) to (5), respectively:

F1/F≤1.6 (2)

i is not less than 4 (3) | F2/F

F3/F≥12 (4)

F4/F≤1.4 (5)

In this way, as described above, by setting the focal lengths of the first lens and the fourth lens large and the focal lengths of the second lens and the third lens small, it is possible to make the energy entering the lens high, thereby achieving a high amount of incident light, and obtain a large angle of field, for example, 30 ° to 48 °.

It will be understood by those skilled in the art that the above-described conditional expressions (2) to (5) are in a parallel relationship and are not in a relationship associated with each other therebetween. That is, in the optical lens according to the embodiment of the present invention, only one or more of conditional expressions (2) to (5) may be satisfied, and the above-described conditional expressions (2) to (5) may be all satisfied.

Preferably, in the above optical lens, the second lens and the third lens satisfy the following conditional expressions (6) and (7), respectively:

0.5≤(R4+d3)/R3≤1.5 (6)

0.5 ≦ (R6 | + d 6)/R7 | ≦ 1.5 (7)

Where R3 is the radius of curvature of the object-side surface of the second lens, R4 is the radius of curvature of the image-side surface of the second lens, d3 is the center thickness of the second lens, R6 is the radius of curvature of the object-side surface of the third lens, R7 is the radius of curvature of the image-side surface of the third lens, and d6 is the center thickness of the third lens.

Also, here, the conditional expressions (6) and (7) are also in a parallel relationship and there is no correlation therebetween. That is, in the optical lens according to the embodiment of the present invention, only one of the conditional expressions (6) and (7) may be satisfied, or both of the conditional expressions (6) and (7) may be satisfied.

In this way, by the arrangement of the symmetrical concentric circular shapes of the second lens and the third lens, small distortions, e.g. within 1%, can be effectively guaranteed.

Also, in the optical lens according to the embodiment of the present invention, the refractive index Nd and the abbe number Vd of the first lens and the fourth lens preferably satisfy: nd is more than or equal to 1.7, and Vd is less than or equal to 55. And, the refractive index Nd and the abbe number Vd of the second lens and the third lens preferably satisfy: nd is less than or equal to 1.6 and Vd is more than or equal to 23.

In addition, as can be understood by those skilled in the art, the optical lens according to the embodiment of the present invention can be applied to other optical lenses that need to achieve high incident light quantity and small distortion and meet the miniaturization requirement, in addition to being used as a receiving end lens of a laser radar. Therefore, the optical lens according to the embodiment of the present invention is not intended to be limited to only the receiving-end lens of the laser radar.

[ numerical example of optical lens ]

Hereinafter, specific embodiments and numerical examples of an optical lens according to an embodiment of the present invention, in which specific numerical values are applied to the respective embodiments, will be described with reference to the drawings and tables.

Some of the lenses used in the embodiments have an aspherical lens surface, and the aspherical surface shape is represented by the following expression (8):

wherein, z (h) is a distance rise from the vertex of the aspherical surface when the aspherical surface is at a position of height h in the optical axis direction.

c is 1/r, r represents the radius of curvature of the lens surface, k is a conic coefficient, A, B, C, D and E are high-order aspheric coefficients, E in the coefficients represents a scientific notation, E-05 represents 10^-5。

In addition, Nd denotes a refractive index, and Vd denotes an abbe number.

First embodiment

As shown in fig. 1, the optical lens according to the first embodiment of the present invention includes, in order from an object side to an image side: a meniscus-shaped first lens L1 having positive power, having a convex object-side first surface S1 and a concave image-side second surface S2; a meniscus-shaped second lens L2 having a negative power, having a convex object-side first surface S3 and a concave image-side second surface S4; diaphragm L3; a meniscus-shaped third lens L4 having positive power, having a concave object-side first surface S6 and a convex image-side second surface S7; a fourth lens L5 having positive optical power, having a first surface S8 convex toward the object side and a second surface S9 as a plane toward the image side; a planar lens L6 having a first surface S10 facing the object side and a second surface S11 facing the image side, typically a protective glass; l7 is a chip.

The lens data of the above lenses are shown in table 1 below:

[ TABLE 1 ]

In the optical lens according to the first embodiment of the present invention, it is preferable that the second lens and the third lens are aspherical lenses, and the conic coefficients k and high-order aspherical coefficients A, B, C, D and E of the first surface S3 and the second surface S4 of the second lens and the first surface S6 and the second surface S7 of the third lens are as shown in table 2 below.

[ TABLE 2 ]

Surface of

k

A

B

C

D

E

3

0.03333708

7.6912E-07

8.7172E-08

-7.5999E-10

6.2705E-12

-6.1236E-15

4

0.000299274

1.3244E-05

6.6660E-07

-4.2133E-08

5.4625E-10

-7.7643E-13

6

-0.03273183

-1.9013E-05

7.1582E-07

-6.5983E-10

-4.4910E-11

5.4625E-13

7

-0.3122766

6.4375E-06

5.1146E-08

9.8094E-11

-3.0050E-12

4.0456E-15

In the optical lens according to the first embodiment of the present invention, the focal length F1 of the first lens, the focal length F2 of the second lens, the focal length F3 of the third lens, the focal length F4 of the fourth lens, the entire group focal length value F of the optical lens, and the optical length TTL of the optical lens and the relationship therebetween, the relationship between the radii R3 and R4 and the thickness d3 of the object-side surface and the image-side surface of the second lens, and the relationship between the radii R6 and R7 and the thickness d6 of the object-side surface and the image-side surface of the third lens are as shown in table 3 below.

[ TABLE 3 ]

F1	61.304403
		F2	-215.128861
F3	593.197686
		F4	45.130238
F	44.8016
		TTL	69.5
F1/F	1.368352983
		F4/F	1.007335408
I F2/F I	4.801812011
		F3/F	13.2405469
TTL/F	1.551283883
		(R4+d3)/R3	1.147072822
(R6 i + d 6)/R7 i	1.475974026

As can be seen from table 3 above, the optical lens according to the first embodiment of the present invention satisfies the aforementioned conditional expressions (1) to (7), thereby achieving a high light-in amount and small distortion while keeping the optical lens miniaturized.

Second embodiment

As shown in fig. 2, the optical lens according to the second embodiment of the present invention, in order from an object side to an image side, comprises: a meniscus-shaped first lens L1 having positive power, having a convex object-side first surface S1 and a concave image-side second surface S2; a meniscus-shaped second lens L2 having a negative power, having a convex object-side first surface S3 and a concave image-side second surface S4; diaphragm L3; a meniscus-shaped third lens L4 having positive power, having a concave object-side first surface S6 and a convex image-side second surface S7; a meniscus-shaped fourth lens L5 having positive power, having a convex object-side first surface S8 and a concave image-side second surface S9; a planar lens L6 having a first surface S10 facing the object side and a second surface S11 facing the image side, typically a protective glass; l7 is a chip.

The lens data for the above lenses are shown in table 4 below:

[ TABLE 4 ]

Surface of	Radius of	Thickness of	Nd	Vd
					1	31.20044	8.718969	1.77	49.6
2	80.65565	0.2
					3	19.80296	8.084195	1.58	30.2
4	14.8141	4.461203
					STO	Infinite number of elements	9.127523
6	-14.25878	8.455949	1.58	30.2
					7	-16.54439	0.2
8	30.60641	10.62163	1.72	38.0
					9	100	11.5569
10	Infinite number of elements	2	1.46	67.8
					11	Infinite number of elements	1
IMA	Infinite number of elements

In the optical lens according to the first embodiment of the present invention, it is preferable that the second lens and the third lens are aspherical lenses, and the conic coefficients k and high-order aspherical coefficients A, B, C, D and E of the first surface S3 and the second surface S4 of the second lens and the first surface S6 and the second surface S7 of the third lens are as shown in table 5 below.

[ TABLE 5 ]

Surface of

k

A

B

C

D

E

3

0.004923737

3.5375E-07

6.3512E-08

-5.9170E-10

2.9997E-12

-4.6936E-15

4

-0.09510785

7.0483E-07

5.7495E-07

-9.5986E-09

1.0303E-10

-3.8332E-13

6

-0.0296257

-5.8110E-06

2.2961E-07

-2.0333E-09

1.5959E-11

-1.0375E-13

7

-0.2224704

4.9119E-06

8.4776E-09

1.0681E-10

-1.3194E-13

-3.2859E-15

In the optical lens according to the first embodiment of the present invention, the relationship among and among the focal length F1 of the first lens, the focal length F2 of the second lens, the focal length F3 of the third lens, the focal length F4 of the fourth lens, the entire group focal length value F of the optical lens, and the optical length TTL of the optical lens, the relationship among and among the radii R3 and R4 and the thickness d3 of the object-side and image-side surfaces of the second lens, and the relationship among and among the radii R6 and R7 and the thickness d6 of the object-side and image-side surfaces of the third lens are shown in table 6 below.

[ TABLE 6 ]

F1	62.671806
		F2	-250.905034
F3	552.269329
		F4	58.986552
F	45.4748
		TTL	64.4264
F1/F	1.378165621
		F4/F	1.297126145
I F2/F I	5.517452171
		F3/F	12.14451364
TTL/F	1.416749496
		(R4+d3)/R3	1.156306683
(R6 i + d 6)/R7 i	1.372956573

As can be seen from table 6 above, the optical lens according to the second embodiment of the present invention satisfies the aforementioned conditional expressions (1) to (7), thereby achieving a high light-in amount and small distortion while keeping the optical lens miniaturized.

In summary, in the optical lens according to the embodiment of the present invention, by optimally setting the shapes of the respective lenses and reasonably distributing the powers of the respective lenses, it is possible to achieve a high light incident amount while keeping the lens compact.

In the optical lens according to the embodiment of the invention, the first lens adopts the meniscus lens with positive focal power, so that more light rays can be collected to enter the optical system, and high light incoming quantity is realized.

In the optical lens according to the embodiment of the invention, the first lens adopts the meniscus shape, so that the caliber of the second lens and the distance between the first lens and the second lens can be effectively reduced, and the optical lens is beneficial to realizing miniaturization.

In the optical lens according to the embodiment of the present invention, by the shape and power setting of the second lens, it is possible to achieve smooth transition of light and reduce aberration generated by the first lens.

In the optical lens according to the embodiment of the present invention, by the shape and power setting of the third lens, it is possible to further reduce aberrations generated by the first lens and the second lens and to facilitate adjustment of the imaging size.

In the optical lens according to the embodiment of the invention, the object side surface of the fourth lens is a convex surface, which is helpful for collecting the emergent light from the third lens and converging the emergent light to the chip.

In the optical lens according to the embodiment of the invention, the second lens and the third lens have approximately the same aperture, so that the cost of the optical lens can be effectively reduced.

In the optical lens according to the embodiment of the present invention, by setting the second lens and the third lens as aspherical lenses, the magnitude of the dispersed spot and the magnitude of distortion can be controlled to provide excellent optical performance.

In the optical lens according to the embodiment of the present invention, by providing the second lens and the third lens as glass aspherical lenses, good thermal stability can be achieved.

In the optical lens according to the embodiment of the present invention, by providing the second lens and the third lens as plastic aspherical lenses whose materials/shapes are substantially uniform, it is possible to offset a defocus change at the time of temperature change to improve thermal stability, and to realize a high light incident amount with a small fluctuation range.

In the optical lens according to the embodiment of the present invention, by setting the second lens and the third lens to be symmetrical concentric circles, distortion can be effectively corrected, and small distortion is ensured.

In the optical lens according to the embodiment of the invention, the second lens and the third lens are arranged to be the approximately concentric plastic lens, so that the processing of the lens is facilitated, and the low cost of the optical lens is realized.

In the optical lens according to the embodiment of the present invention, by providing a large diaphragm aperture, more reflected light rays can be received.

In the optical lens according to the embodiment of the present invention, by setting the focal lengths of the first lens and the fourth lens to be large and the focal lengths of the second lens and the third lens to be small, it is possible to make the energy entering the lens high, thereby achieving a high light-entering amount and obtaining a large angle of field.

In the optical lens according to the embodiment of the present invention, by setting the refractive index and the abbe number of the first lens to the fourth lens, it is helpful to realize a smooth transition of light in the entire optical system, thereby obtaining a high incident light amount and a large angle of field.

[ arrangement of laser Radar ]

According to another aspect of the embodiments of the present invention, there is provided a laser radar including an optical lens serving as a receiving-end lens, the optical lens including, in order from an object side to an image side: the first lens is a meniscus lens with positive focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens is a meniscus lens with negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens element having a meniscus shape with a positive refractive power, the third lens element having a concave object-side surface and a convex image-side surface; and a fourth lens having a positive refractive power, the object-side surface of the fourth lens being a convex surface.

FIG. 3 is a schematic block diagram of a lidar in accordance with an embodiment of the invention. As shown in fig. 3, the laser radar 100 according to the embodiment of the present invention includes an optical lens 101, wherein the optical lens 101 serves as a receiving-end lens of the laser radar 100. In the optical lens assembly, an image-side surface of the fourth lens element is a flat surface, or an image-side surface of the fourth lens element is a concave surface.

In the above optical lens, the second lens and the third lens are aspherical lenses.

TTL/F≤1.6 (1)

wherein, F is the whole group focal length value of the optical lens, and TTL is the optical length of the optical lens.

In the above optical lens, focal lengths of the first lens to the fourth lens satisfy the following conditional expressions (2) to (5), respectively:

F1/F≤1.6 (2)

i is not less than 4 (3) | F2/F

F3/F≥12 (4)

F4/F≤1.4 (5)

Wherein F1 is the focal length of the first lens, F2 is the focal length of the second lens, F3 is the focal length of the third lens, F4 is the focal length of the fourth lens, and F is the entire focal length of the optical lens.

In the above optical lens, the second lens and the third lens satisfy the following conditional expressions (6) and (7), respectively:

0.5≤(R4+d3)/R3≤1.5 (6)

0.5 ≦ (R6 | + d 6)/R7 | ≦ 1.5 (7)

Wherein R3 is a radius of curvature of an object-side surface of the second lens, R4 is a radius of curvature of an image-side surface of the second lens, d3 is a center thickness of the second lens, R6 is a radius of curvature of an object-side surface of the third lens, R7 is a radius of curvature of an image-side surface of the third lens, and d6 is a center thickness of the third lens.

Here, it can be understood by those skilled in the art that other details of the optical lens in the laser radar according to the embodiment of the present invention are the same as those described above with respect to the optical lens according to the embodiment of the present invention, and the aforementioned numerical examples of the optical lens according to the first embodiment and the second embodiment of the present invention may be adopted, so that no trace is made to avoid redundancy.

According to the optical lens and the laser radar of the embodiment of the invention, the shapes of the lenses are optimally set and the focal powers of the lenses are reasonably distributed, so that the miniaturization of the lenses is kept and the high light incident quantity is realized.

According to the optical lens and the laser radar provided by the embodiment of the invention, the first lens adopts the meniscus lens with positive focal power, so that more light rays can be collected and enter the optical system, and the high light-entering quantity is realized.

According to the optical lens and the laser radar of the embodiment of the invention, the first lens adopts the meniscus shape, so that the caliber of the second lens and the distance between the first lens and the second lens can be effectively reduced, and the optical lens is beneficial to realizing miniaturization.

According to the optical lens and the laser radar of the embodiment of the invention, through the shape and the focal power setting of the second lens, smooth transition of light rays can be realized, and aberration generated by the first lens is reduced.

According to the optical lens and the laser radar of the embodiment of the invention, through the shape and the power setting of the third lens, the aberration generated by the first lens and the second lens can be further reduced, and the adjustment of the imaging size is facilitated.

According to the embodiment of the invention, the optical lens and the laser radar are convex through the object side surface of the fourth lens, so that the collection of emergent rays from the third lens is facilitated and the rays are converged to a chip.

According to the optical lens and the laser radar provided by the embodiment of the invention, the second lens and the third lens are set to have approximately the same calibers, so that the cost of the optical lens can be effectively reduced.

According to the optical lens and the laser radar of the embodiment of the invention, the second lens and the third lens are arranged to be the aspheric lens, so that the size of the dispersed spot and the size of the distortion can be controlled and excellent optical performance can be provided.

According to the optical lens and the laser radar of the embodiment of the invention, the second lens and the third lens are glass aspheric lenses, so that good thermal stability can be realized.

According to the optical lens and the laser radar provided by the embodiment of the invention, the second lens and the third lens are plastic aspheric lenses with basically consistent materials/shapes, so that defocusing change during temperature change can be counteracted, the thermal stability is improved, and high light input quantity with a small fluctuation range is realized.

According to the optical lens and the laser radar provided by the embodiment of the invention, the second lens and the third lens are arranged in the symmetrical concentric circle shape, so that the distortion can be effectively corrected, and the small distortion is ensured.

According to the optical lens and the laser radar provided by the embodiment of the invention, the second lens and the third lens are arranged into the concentric circular plastic lenses, so that the processing of the concentric circular lenses is facilitated, and the low cost of the optical lens is realized.

The optical lens and the laser radar according to the embodiment of the invention can receive more reflected light by providing a large diaphragm aperture.

According to the optical lens and the laser radar of the embodiment of the invention, by setting the focal lengths of the first lens and the fourth lens to be large and the focal lengths of the second lens and the third lens to be small, the energy entering the lens can be made high, so that a high light-entering amount is realized, and a large field angle is obtained.

The optical lens and the laser radar according to the embodiment of the invention help to realize the smooth transition of light in the whole optical system by setting the refractive index and the abbe number of the first lens to the fourth lens, thereby obtaining high light incoming quantity and large field angle.

Additional lenses may also be disposed in the optical lens and lidar according to embodiments of the present invention. In this case, the optical lens and the imaging apparatus according to the embodiment of the present invention may be configured with four or more lenses, and the lenses include additional lenses arranged in addition to the first lens to the four lenses described above.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims

1. An optical lens in which the number of lenses having power is four, that is, a first lens, a second lens, a third lens, and a fourth lens, the first lens to the fourth lens being arranged in order from an object side to an image side,

the first lens is a meniscus lens with positive focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;

the second lens is a meniscus lens with negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

the third lens is a meniscus lens with positive focal power, the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; and

the fourth lens is a lens with positive focal power, and the object side surface of the fourth lens is a convex surface;

focal lengths of the first lens to the fourth lens satisfy the following conditional expression (3):

I4/F2/F I5.517452171 (3)

Wherein F2 is the focal length of the second lens, and F is the whole set of focal length values of the optical lens.

2. An optical lens according to claim 1,

the image side surface of the fourth lens is a plane; or

The image side surface of the fourth lens is a concave surface.

3. An optical lens according to claim 1, characterized in that at least one of the second lens and the third lens is an aspherical lens.

4. An optical lens according to claim 3, characterized in that the second lens and the third lens have shapes close to concentric circles.

5. An optical lens according to claim 4, characterized in that the second and third lenses are plastic lenses.

6. An optical lens according to any one of claims 1 to 3, characterized by further comprising:

a large aperture stop located between the second lens and the third lens.

7. An optical lens according to any one of claims 1 to 3, wherein the first lens to the fourth lens satisfy the following conditional expression (1):

TTL/F≤1.6 (1)

8. An optical lens according to any one of claims 1 to 3, wherein focal lengths of the first lens to the fourth lens satisfy the following conditional expression (2):

F1/F≤1.6 (2)

9. An optical lens according to any one of claims 1 to 3, wherein focal lengths of the first lens to the fourth lens satisfy the following conditional expression (4):

F3/F≥12 (4)

where F3 is the focal length of the third lens, and F is the entire set of focal length values of the optical lens.

10. An optical lens according to any one of claims 1 to 3, wherein focal lengths of the first lens to the fourth lens satisfy the following conditional expression (5):

F4/F≤1.4 (5)

11. An optical lens according to any one of claims 1 to 3, wherein the second lens and the third lens satisfy the following conditional expression (6):

0.5≤(R4+d3)/R3≤1.5 (6)

wherein R3 is a radius of curvature of an object-side surface of the second lens, R4 is a radius of curvature of an image-side surface of the second lens, and d3 is a center thickness of the second lens.

12. An optical lens according to any one of claims 1 to 3, wherein the second lens and the third lens satisfy the following conditional expression (7):

0.5 ≦ (R6 | + d 6)/R7 | ≦ 1.5 (7)

Wherein R6 is a radius of curvature of an object-side surface of the third lens, R7 is a radius of curvature of an image-side surface of the third lens, and d6 is a center thickness of the third lens.

13. A lidar characterized by comprising the optical lens of any one of claims 1 to 12 as a receiving-end lens.