CN220105399U - Optical lens and laser radar - Google Patents

Abstract

The utility model provides an optical lens and a laser radar, and relates to the technical field of radars. The optical lens includes a first lens, a second lens, and a third lens arranged in order from an object side to an image side along an optical axis extending direction. Wherein the first lens has positive focal power; the second lens has positive 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 has negative focal power, and one of the object side surface and the image side surface of the third lens is concave, and the other is concave or plane. The total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is more than or equal to 0.4 and less than or equal to 0.45. The optical lens can be miniaturized while having a long focal length. The optical lens is also beneficial to reducing distortion and keeping the consistency of radar resolution and measuring range. The laser radar provided by the utility model comprises the optical lens, is easy to realize miniaturization, and has a better detection effect.

Description

Optical lens and laser radar

Technical Field

The utility model relates to the technical field of radars, in particular to an optical lens and a laser radar.

Background

As an information sensing unit, the laser radar is widely applied to the fields of industrial sensing, automatic driving and the like. The principle is that the radar emits one or more laser beams to the outside, and the detection function is realized by receiving laser signals reflected by the outside. The laser radar mainly comprises a transmitting module, a receiving module, a scanning module and a signal processing module, wherein the transmitting module is used for transmitting detection laser, the receiving module is used for receiving echo signals, the scanning module is used for expanding the angle of radar detection, and the signal processing module is used for converting signals received by the receiving module into environment information. If the receiving detector is a detection array composed of a plurality of detector units, the distortion of the receiving lens needs to be as small as possible in order to maintain the consistency of the resolution of the receiving system. The resolution of the radar is related to the focal length of the receiving lens, and the longer the focal length is, the higher the resolution is.

However, the mechanical size of the long-focus lens is often larger, and the conventional laser radar receiving lens is difficult to miniaturize equipment and simultaneously meets the requirements of long focal length and low distortion.

Disclosure of Invention

An object of the present utility model is to provide an optical lens and a laser radar, which can satisfy the demands of miniaturization, long focal length, and low distortion. The laser radar has the advantages of small volume, high resolution and good detection effect.

Embodiments of the utility model may be implemented as follows:

in a first aspect, the present utility model provides an optical lens comprising, in order from an object side to an image side along an optical axis extending direction:

a first lens having positive optical power;

the second lens is provided with positive 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 provided with negative focal power, one of the object side surface and the image side surface of the third lens is a concave surface, and the other is a concave surface or a plane;

wherein, the optical total length TTL and the effective focal length f of the optical lens satisfy the following conditions: TTL/f is more than or equal to 0.4 and less than or equal to 0.45.

The optical lens provided by the utility model can be used as a receiving lens of the laser radar, and the optical lens can be miniaturized and has a longer focal length by selecting the focal power of each lens, selecting the shapes of the second lens and the third lens and controlling the relation between the total optical length TTL and the effective focal length f, so that the optical lens is favorable for improving the resolution of the optical lens as the laser radar. In addition, the optical lens is beneficial to reducing distortion and keeping the consistency of radar resolution and measuring range. Through the combination of positive and negative focal power of each lens, aberration can be reduced, the incidence angle of the principal ray of the image plane of the optical lens is reduced, and the signal-to-noise ratio of echo signals is increased.

In an alternative embodiment, the object-side surface of the first lens element is convex, and the image-side surface is concave. The first lens is a meniscus lens with a convex object side surface and a concave image side surface, so that the length of the lens is reduced on the premise of ensuring smaller distortion and higher resolution.

In an alternative embodiment, the focal length f1 of the first lens, the focal length f2 of the second lens, and the focal length f3 of the third lens satisfy the following relationship with the effective focal length f of the optical lens:

f1/f≤0.43，f2/f≤0.49，|f3/f|≥0.049。

by designing the focal length of each lens and the effective focal length of the optical lens to satisfy the above-mentioned relationship, the optical total length of the optical lens can be effectively controlled, and the purpose of miniaturization of the apparatus can be achieved; and the optical distortion is ensured to be smaller, and the detection capability of the laser radar is improved.

In an alternative embodiment, the maximum field angle FOV of the optical lens satisfies: FOV is more than or equal to 1.6 degrees and less than or equal to 2.2 degrees. When the optical lens is applied to the laser radar, the resolution of the laser radar can be improved due to the relatively small field angle, and the laser can output high-quality and high-density point clouds, so that the detection precision of the laser radar can be ensured.

In an alternative embodiment, the image plane chief ray angle CRA of the optical lens satisfies: CRA is less than or equal to 8.5 degrees. The main light incidence angle CRA is controlled in a smaller range, so that the center wavelength offset of the narrow-band filter is reduced, the bandwidth is maintained in a smaller range, the suppression of ambient light is facilitated, and the signal-to-noise ratio of a received signal is improved.

In an alternative embodiment, the radius of curvature of the object-side surface of the first lens is 30-35 mm, and the radius of curvature of the image-side surface of the first lens is 650-750 mm;

and/or the curvature radius of the object side surface of the second lens is 15-20 mm, and the curvature radius of the image side surface of the second lens is 20-30 mm;

and/or the curvature radius of the object side surface of the third lens is-20 to-30 mm, and the curvature radius of the image side surface of the third lens is 5 to 10mm.

By reasonably designing the curvature radiuses of the object side surface and the image side surface of each lens, the imaging quality can be improved, and the distortion can be reduced; the lens length is also reduced, and the miniaturization of the equipment is realized.

In an alternative embodiment, the lens further comprises a window glass, and the window glass is arranged on the image side of the third lens. The window glass can prevent foreign matters from entering the optical lens to influence the work of the optical lens; the photosensitive surface of the receiving chip can be protected from being polluted by dust and dirt, and radar detection capability is prevented from being reduced due to dirt on the photosensitive surface.

In an alternative embodiment, the optical lens further comprises a narrow-band filter, and the narrow-band filter is arranged between the third lens and the window glass. The narrow-band filter can perform wavelength screening on received light rays, and inhibit energy of light rays with other wavelengths except for laser wave bands emitted by the laser radar, so that the signal-to-noise ratio is improved.

In an alternative embodiment, the thickness of the first lens is 4-6 mm at the optical axis position;

and/or the thickness of the second lens is 7-9 mm;

and/or the thickness of the third lens is 1.5-2.5 mm;

and/or the thickness of the narrow-band filter is 0.2-0.5 mm;

and/or the thickness of the window glass is 0.3-0.6 mm.

Through reasonable selection of the thicknesses of each lens, the narrow-band optical filter and the window glass, the miniaturization of the equipment can be realized under the condition of ensuring the imaging quality.

In an alternative embodiment, the distance between the first lens and the second lens is 0.4-0.6 mm at the position of the optical axis;

and/or the distance between the second lens and the third lens is 13-16 mm;

and/or the distance between the third lens and the narrow-band filter is 2.5-3.5 mm;

and/or the distance between the narrow-band filter and the window glass is 18-22 mm;

and/or the spacing between the window glass and the image plane of the optical lens is 0.3-0.5 mm.

Through reasonable selection of the distance between each lens, the narrow-band optical filter and the window glass, the miniaturization of the equipment can be realized under the condition of ensuring the imaging quality.

In an alternative embodiment, the lens further comprises an aperture stop, and the aperture stop is disposed on the object side surface of the first lens. The first lens is arranged on the object side surface of the first lens, so that light rays incident on the optical lens are converged on the receiving chip, the receiving caliber is maximized, the energy of received echo signals is increased, and the detection capability of the laser radar is improved.

In an alternative embodiment, F is equal to or greater than 4.5 and equal to or less than 5.9. By setting a larger aperture value F (namely a smaller aperture), the focal depth of the optical lens can be increased, the sensitivity of the distance between the receiving chip and the optical lens is reduced, and the adjustment difficulty of the optical lens is reduced.

In an alternative embodiment, the first lens, the second lens and the third lens are spherical lenses. The spherical lens can meet the performance requirement, and is beneficial to reducing the processing cost.

In an alternative embodiment, the refractive index of the first lens is 1.45-1.65, and the refractive index of the second lens and the third lens is 1.68-1.96. By reasonably selecting the refractive index of each lens and matching with the reasonable design of the shape and the size of each lens, the imaging quality of the optical lens and the miniaturization of the equipment are improved.

In an alternative embodiment, the abbe numbers of the first lens, the second lens and the third lens decrease in order.

In an alternative embodiment, the abbe number of the first lens is 60 to 70, the abbe number of the second lens is 50 to 60, and the abbe number of the third lens is 15 to 25.

The Abbe number of each lens is reasonably selected, so that the imaging quality of the lens is improved, and the detection performance of the laser radar is improved.

In a second aspect, the present utility model provides a laser radar comprising an optical lens as provided in any one of the implementations of the first aspect. Due to the optical lens, the laser radar is easy to realize miniaturization and has a better detection effect.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present utility model and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an optical lens according to an embodiment of the utility model;

FIG. 2 is a graph of F-Theta distortion of an optical lens in accordance with one embodiment of the present utility model;

FIG. 3 is a graph showing the relative illuminance of an optical lens according to an embodiment of the present utility model.

Icon: 100-an optical lens; 110-a first lens; 120-a second lens; 130-a third lens; 140-a narrowband filter; 150-window glass.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present utility model, it should be noted that, if the terms "upper", "lower", "inner", "outer", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present utility model and simplifying the description, and it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus it should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, if any, are used merely for distinguishing between descriptions and not for indicating or implying a relative importance.

It should be noted that the features of the embodiments of the present utility model may be combined with each other without conflict.

The resolution of the lidar is related to the focal length of the receiving lens, the longer the focal length, the higher the resolution. However, the mechanical size of the long-focus lens is often large, which is unfavorable for miniaturization of the laser radar. In addition, in order to increase the detection capability of the lidar, it is necessary for the receiving lens to receive more laser signals emitted from the radar reflected by the outside, while reducing the reception of other ambient spurious signals such as sunlight. In order to suppress the ambient light signal and improve the signal to noise ratio of the radar, a narrow-band filter needs to be introduced into a receiving lens. The passband bandwidth of the narrowband filter determines the effect of ambient light suppression, and the narrower the bandwidth, the better the suppression of the ambient light. The center wavelength of the filter is related to the chief ray incidence angle CRA (chief ray angle), and when CRA is large, the filter center wavelength shift increases, resulting in a wide bandwidth, which is disadvantageous for ambient light suppression. Therefore, in the design of the receiving lens, CRA needs to be reduced, so that environmental light is better suppressed. In addition, if the receiving detector of the lidar is a detection array composed of a plurality of detector units, the distortion of the receiving lens needs to be as small as possible in order to maintain the consistency of the resolution of the receiving system. Meanwhile, in order to ensure that the detection capability of different fields of view is the same, the relative illumination of the image plane of the receiving system is high.

However, it is often difficult to achieve a long focal length, low distortion, low CRA, and the like in a small-sized receiving lens used in the laser radar of the related art. The receiving lens is difficult to achieve better performance in miniaturization, and the detection effect of the laser radar is affected.

The embodiment of the utility model provides an optical lens and a laser radar comprising the optical lens. The miniaturization and the related performance of the equipment can be considered.

Fig. 1 is a schematic diagram of an optical lens 100 according to an embodiment of the utility model. As shown in fig. 1, the optical lens 100 provided in the embodiment of the utility model can be applied to a laser radar as a receiving lens of the laser radar. The optical lens 100 of the present embodiment includes a first lens 110, a second lens 120, and a third lens 130 sequentially arranged from an object side to an image side (i.e., from left to right in fig. 1) along an extending direction of an optical axis (a dotted line L in the drawing), and may further include a narrow band filter 140 and a window glass 150 sequentially arranged from the object side to the image side along the extending direction of the optical axis (the dotted line L in the drawing). Wherein the first lens 110 has positive optical power, the second lens 120 has positive optical power, and the third lens 130 has negative optical power. The optical total length TTL and the effective focal length f of the optical lens 100 satisfy: TTL/f is more than or equal to 0.4 and less than or equal to 0.45. The optical total length TTL of the optical lens 100 is a distance from the object side surface of the first lens element 110 to the image plane of the optical lens 100. The optical lens 100 of the present embodiment can effectively shorten the total optical length thereof, and achieve the purpose of miniaturization of the apparatus.

In the embodiment shown in fig. 1, the object-side surface of the first lens element 110 is convex, and the image-side surface is concave; the second lens element 120 has a convex object-side surface and a concave image-side surface; the object-side surface and the image-side surface of the third lens element 130 are concave. In alternative other embodiments, the object-side surface and the image-side surface of the first lens element 110 may be convex, or one of them may be convex and the other may be planar. In alternative other embodiments, one of the object-side surface and the image-side surface of the third lens 130 is concave, and the other is planar or concave.

In this embodiment, the radius of curvature of the object-side surface of the first lens element 110 is 30-35 mm, and the radius of curvature of the image-side surface of the first lens element 110 is 650-750 mm; the radius of curvature of the object-side surface of the second lens element 120 is 15-20 mm, and the radius of curvature of the image-side surface of the second lens element 120 is 20-30 mm; the radius of curvature of the object-side surface of the third lens element 130 is-20 to-30 mm, and the radius of curvature of the image-side surface of the third lens element 130 is 5 to 10mm. It should be noted that the radius of curvature is exactly that the center of curvature is located at the image side of the lens, i.e. the curved surface arches towards the object side; the radius of curvature being negative means that the center of curvature is located on the object side of the lens, i.e. the curved surface arches towards the image side. In other words, the radius of curvature of the object side is positive, the object side is convex, and vice versa; the radius of curvature of the image side surface is positive, the image side surface is concave, and vice versa.

Further, at the optical axis position, the distance between the first lens 110 and the second lens 120 is 0.4-0.6 mm; the distance between the second lens 120 and the third lens 130 is 13-16 mm; the distance between the third lens 130 and the narrow-band filter 140 is 2.5-3.5 mm; the distance between the narrow-band filter 140 and the window glass 150 is 18-22 mm; the distance between the window glass 150 and the image plane of the optical lens 100 is 0.3 to 0.5mm. It should be noted that the spacing between two components refers to the gap width between the two, i.e. the air thickness.

Further, at the optical axis position, the thickness of the first lens 110 is 4 to 6mm; the thickness of the second lens 120 is 7-9 mm; the thickness of the third lens 130 is 1.5-2.5 mm; the thickness of the narrow band filter 140 is 0.2-0.5 mm; the thickness of the window glass 150 is 0.3 to 0.6mm.

Further, in the present embodiment, the focal length f1 of the first lens 110, the focal length f2 of the second lens 120, and the focal length f3 of the third lens 130 satisfy the following relationship with the effective focal length f of the optical lens 100: and f1/f is less than or equal to 0.43, f2/f is less than or equal to 0.49, and f3/f is more than or equal to 0.049.

The optical lens 100 of the present embodiment enables the optical lens 100 to have a smaller size in the direction in which the optical axis extends, and to maintain a longer focal length and to improve the resolution of the lidar by designing the focal power, shape, size, and pitch of each component of each lens. In addition, the optical lens 100 balances distortion and relative illumination of an image plane, maintains consistency of radar resolution and range, and reduces aberration of the optical lens 100.

In this embodiment, the narrowband filter 140 is a flat plate perpendicular to the optical axis, and is used for wavelength filtering the received light, so that the light passing through it has a narrower wavelength range, and the narrower wavelength range should include the wavelength of the detection laser emitted by the emitting module of the laser radar. By providing the narrow band filter 140, the light passing through the optical lens 100 is more laser signals reflected by the outside, and other environmental stray signals such as sunlight are reduced. The narrowband filter 140 can suppress the ambient light signal and improve the signal-to-noise ratio of the lidar. The passband bandwidth of the narrowband filter 140 determines the effect of ambient light suppression, the narrower the bandwidth the better the ambient light suppression. Since the center wavelength of the narrowband filter 140 is related to the chief ray incidence angle CRA, when CRA is large, the center wavelength shift increases, resulting in a widening of the bandwidth, which is disadvantageous for the ambient light suppression. The optical lens 100 of the present embodiment is designed to have a smaller incidence angle CRA of principal ray on the image plane by designing the focal power, shape and pitch of each lens. In an alternative embodiment, the incidence angle CRA of the principal ray on the image plane of the optical lens 100 is less than or equal to 8.5 °, and the optical lens 100 has a better effect of suppressing ambient light, and can increase the signal-to-noise ratio of the radar echo signal.

In the embodiment of the present utility model, the optical lens 100 further includes an aperture stop (not shown in the drawings). In this embodiment, the aperture stop is disposed on the object side surface of the first lens element 110, so that the receiving aperture can be maximized, so that the light incident on the optical lens 100 is finally converged on the detector, the energy of the received echo signal is increased, the detection capability of the laser radar is improved, and the relative illuminance of the image plane is also improved.

In the present embodiment, F is equal to or greater than 4.5 and equal to or less than 5.9. The aperture value F is at a higher level, so that the focal depth of the optical lens 100 can be increased, thereby reducing the sensitivity of the distance between the receiving chip and the receiving lens and reducing the adjustment difficulty. It can be understood that the theoretical installation position of the receiving chip is the image plane position of the optical lens 100, and even if there is a slight deviation of the position of the receiving chip in the extending direction of the optical axis, the receiving effect is not easily affected, so that the difficulty of adjustment can be reduced.

In the present embodiment, the first lens 110, the second lens 120 and the third lens 130 are all spherical lenses. The spherical lens processing process is relatively simple, and the cost of the optical lens 100 can be reduced. In alternative other embodiments, the image side and the object side of the first lens element 110, the second lens element 120, and the third lens element 130 may be aspheric.

Optionally, the abbe numbers of the first lens 110, the second lens 120, and the third lens 130 decrease sequentially. In the present embodiment, the abbe number of the first lens 110 is 60 to 70, the abbe number of the second lens 120 is 50 to 60, and the abbe number of the third lens 130 is 15 to 25. Alternatively, the refractive index of the first lens 110 is 1.45-1.65, and the refractive index of the second lens 120 and the third lens 130 is 1.68-1.96. The materials of the first lens 110, the second lens 120, and the third lens 130 may be selected to be glass. The glass has better stability, can reduce the temperature sensitivity of the focal length of the optical lens 100, and increase the working stability of the laser radar in different temperature environments, thereby being suitable for more complex environments.

In the present embodiment, the maximum field angle FOV (field of view) of the optical lens 100 satisfies: FOV is more than or equal to 1.6 degrees and less than or equal to 2.2 degrees. The resolution ratio of the laser radar can be improved due to the relatively small field angle, and the laser radar can output high-quality and high-density point clouds, so that the detection precision is improved.

In this embodiment, the window glass 150 is used to protect the photosensitive surface of the receiving chip from dirt and contamination, and prevent the radar detection capability from being reduced due to dirt and contamination of the photosensitive surface.

The following table shows the parameters of the optical lens 100 according to an embodiment of the present utility model.

In the table above, each part (except for the image plane) corresponds to two thickness values, the upper thickness value representing the own thickness of the part, and the lower thickness value representing the spacing between the part and the next part, i.e. the air thickness. ST represents the setting position of the aperture stop.

The F-Theta distortion curve and the relative illuminance curve of the optical lens 100 of the above table embodiment are shown in fig. 2 and 3. In fig. 2 the field angle is in degrees and it can be seen from fig. 2 that the distortion increases more slowly as the deflection of the field angle increases, the distortion being only 0.27% at a position deflected 0.9 ° from the centre of the field of view, at a lower level. It will be appreciated that the distortion is also 0.27% at a location offset from the center of the field of view by-0.9 deg. due to the symmetry of the lens. As can be seen from fig. 3, the relative illuminance decreases gradually as the deflection of the angle of view increases, and 98% remains at the position deflected by 0.9 ° from the center of the field of view. Similarly, due to the symmetry of the lens, the relative illuminance is 98% at the position deviated from the center of the field of view by-0.9 °. Therefore, the optical lens 100 of the embodiment has the advantages of low distortion and high relative illuminance of the edge field of view, and can improve the resolution of different fields of view and the consistency of detection capability (such as measuring range) when being used in a laser radar.

The optical lens provided by the embodiment of the utility model can be called an optical module, the name of the optical lens is not limited, and the optical lens 100 can be applied to various electronic devices, such as a laser radar, an automobile, and the like.

The embodiment of the present utility model also provides a laser radar (not shown in the drawings), which includes the optical lens 100 provided in the above embodiment of the present utility model. Alternatively, the optical lens 100 may be disposed in a receiving module of the lidar. It should be appreciated that lidar should also include a transmitting module and other modules for implementing detection functions, such as a scanning module and a signal processing module. The structure and operation principle of the above modules may refer to the prior art, and will not be described herein.

Optionally, the receiving module further includes a receiving chip, and the receiving chip may be disposed at an image plane position of the optical lens 100 to receive the echo signal.

In summary, the optical power, the shape, the size and the spacing between the components of each lens in the optical lens 100 are designed in the embodiment of the present utility model, so that the optical lens 100 and the laser radar have the following advantages:

the focal length of the lens is increased and the resolution is improved while the miniaturization is realized;

by combining positive and negative focal powers of the lenses, aberration is reduced, an image plane CRA of the optical lens 100 is reduced, and a signal-to-noise ratio of a radar echo signal is increased;

by setting the first lens 110 to be positive focal power, the second lens 120 to be positive focal power, and the third lens 130 to be negative focal power, the length of the optical lens 100 can be shortened (to 55 mm), and the image plane CRA can be reduced;

the consistency of radar resolution and range is maintained by balancing the distortion of the optical lens 100 and the relative illuminance of the image plane;

by arranging the aperture diaphragm on the object side surface of the first lens 110, the receiving aperture is maximized, the energy of the received echo signal is increased, and the detection capability of the radar is improved;

by increasing the aperture value F of the receiving lens, the focal depth of the optical lens 100 is increased, the distance sensitivity between the receiving chip and the optical lens 100 is reduced, and the adjustment difficulty is reduced;

by balancing the refractive index and abbe number of each lens of the optical lens 100, the temperature sensitivity of the focal length of the optical lens 100 is reduced, and the working stability of the laser radar in different temperature environments is increased.

The optical lens 100 uses only three lenses and allows the use of spherical lenses for cost reduction purposes.

The present utility model is not limited to the above embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present utility model are intended to be included in the scope of the present utility model. Therefore, the protection scope of the utility model is subject to the protection scope of the claims.

Claims (17)

1. An optical lens comprising, in order from an object side to an image side along an optical axis extending direction:

a first lens having positive optical power;

the second lens is provided with positive 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 having negative optical power, wherein one of an object side surface and an image side surface of the third lens is a concave surface, and the other is a concave surface or a plane;

wherein, the total optical length TTL and the effective focal length f of the optical lens satisfy the following conditions: TTL/f is more than or equal to 0.4 and less than or equal to 0.45.

2. The optical lens of claim 1, wherein the first lens element has a convex object-side surface and a concave image-side surface.

3. The optical lens according to claim 1 or 2, wherein a focal length f1 of the first lens, a focal length f2 of the second lens, and a focal length f3 of the third lens satisfy the following relationship with an effective focal length f of the optical lens:

f1/f≤0.43，f2/f≤0.49，|f3/f|≥0.049。

4. the optical lens according to claim 1 or 2, characterized in that the maximum field angle FOV of the optical lens satisfies: FOV is more than or equal to 1.6 degrees and less than or equal to 2.2 degrees.

5. Optical lens according to claim 1 or 2, characterized in that the image plane chief ray angle of incidence CRA of the optical lens satisfies: CRA is less than or equal to 8.5 degrees.

6. The optical lens according to claim 1 or 2, wherein a radius of curvature of an object side surface of the first lens is 30 to 35mm, and a radius of curvature of an image side surface of the first lens is 650 to 750mm;

and/or the curvature radius of the object side surface of the second lens is 15-20 mm, and the curvature radius of the image side surface of the second lens is 20-30 mm;

and/or the curvature radius of the object side surface of the third lens is-20 to-30 mm, and the curvature radius of the image side surface of the third lens is 5 to 10mm.

7. The optical lens according to claim 1 or 2, further comprising a window glass provided on an image side of the third lens.

8. The optical lens of claim 7, further comprising a narrowband filter disposed between the third lens and the window glass.

9. The optical lens according to claim 8, wherein a thickness of the first lens at the optical axis position is 4 to 6mm;

and/or the thickness of the second lens is 7-9 mm;

and/or the thickness of the third lens is 1.5-2.5 mm;

and/or the thickness of the narrow-band filter is 0.2-0.5 mm;

and/or the thickness of the window glass is 0.3-0.6 mm.

10. The optical lens according to claim 8, wherein a distance between the first lens and the second lens at the optical axis position is 0.4 to 0.6mm;

and/or the distance between the second lens and the third lens is 13-16 mm;

and/or the distance between the third lens and the narrow-band filter is 2.5-3.5 mm;

and/or the distance between the narrow-band filter and the window glass is 18-22 mm;

and/or the distance between the window glass and the image plane of the optical lens is 0.3-0.5 mm.

11. The optical lens according to claim 1 or 2, further comprising an aperture stop provided at an object side surface of the first lens.

12. The optical lens of claim 11, wherein the optical lens has an aperture value of 4.5.ltoreq.f.ltoreq.5.9.

13. The optical lens of claim 1 or 2, wherein the first lens, the second lens and the third lens are spherical lenses.

14. The optical lens according to claim 1 or 2, wherein the refractive index of the first lens is 1.45-1.65, and the refractive indices of the second lens and the third lens are 1.68-1.96.

15. The optical lens according to claim 1 or 2, wherein abbe numbers of the first lens, the second lens, and the third lens decrease in order.

16. The optical lens of claim 15, wherein the first lens has an abbe number of 60 to 70, the second lens has an abbe number of 50 to 60, and the third lens has an abbe number of 15 to 25.

17. A lidar comprising the optical lens of any of claims 1-16.