LiDAR Transmitter System

Abstract

The present application provides a laser radar transmitting system, which belongs to the field of optical technology. The laser radar transmitting system includes a first lens, a second lens and a light source; wherein the first lens includes a plurality of arrays of sub-lenses; the light source includes a plurality of arrays of sub-light sources; the first lens and the second lens are coaxial and are sequentially arranged on the light-emitting side of the light source; the sub-super lens and the sub-light source are in a mapping relationship. The laser radar transmitting system reduces the number of lenses of the laser radar transmitting system by using the first lens and the second lens formed by the sub-lens array, thereby reducing the total system length and working distance of the laser radar transmitting system, and promoting the miniaturization and lightweight of the laser radar transmitting system.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and in particular to a laser radar transmitting system. Background Art

[0002] Lidar (Laser Detecting and Ranging) is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of a target. Usually, a Lidar includes a transmitting system, a receiving system, an information processing system and a scanning system. Among them, the Lidar transmitting system includes an optical system composed of multiple groups of refractive lenses and a light source.

[0003] Existing technology uses micro-vibration mirrors (MEMS, Micro-Electro-Mechanical System) to replace traditional scanning mechanisms, thereby reducing the size and weight of the LiDAR and achieving miniaturization and lightweight of the LiDAR.

[0004] However, the method of miniaturizing and lightweighting LiDAR by reducing the scanning mechanism has reached a bottleneck, so there is an urgent need for a smaller and lighter LiDAR. Summary of the invention

[0005] In order to solve the technical problem that the miniaturization and lightweighting of laser radar in the prior art are bottlenecked, the embodiment of the present application provides a laser radar transmitting system. The laser radar transmitting system includes a first lens, a second lens and a light source;

[0006] Wherein, the first lens comprises a plurality of arrays of sub-lenses;

[0007] The light source comprises a plurality of arrays of sub-light sources;

[0008] The first lens and the second lens are coaxial and are sequentially arranged on the light emitting side of the light source;

[0009] The sub-lens and the sub-light source are in a mapping relationship.

[0010] Optionally, the sub-lens is a superlens or a microlens array.

[0011] Optionally, the sub-lens and the sub-light source are mapped one-to-one.

[0012] Optionally, the ratio of the working distance to the equivalent focal length of the laser radar transmitting system is less than or equal to 0.1.

[0013] Optionally, the ratio of the total system length of the laser radar transmitting system to the equivalent focal length is less than or equal to 0.1.

[0014] Optionally, the working distance of the laser radar transmitting system is less than or equal to 8 mm.

[0015] Optionally, the total system length of the laser radar transmitting system is less than or equal to 10 times the working distance.

[0016] Optionally, the laser radar transmitting system at least satisfies:

[0017] ;

[0018] Wherein, θ is the half divergence angle of the sub-light source; f MLA is the focal length of the sub-lens; D is the aperture of the sub-lens; h is the diameter of the sub-light source; and P is the spacing between adjacent sub-light sources.

[0019] Optionally, the laser radar transmitting system at least satisfies:

[0020] ;

[0021] Among them, 2θ n is the divergence angle of the second light after being collimated by the sub-lens; f MLA is the focal length of the sub-lens; h is the radius of the sub-light source.

[0022] Optionally, the second lens is a monolithic metalens.

[0023] Optionally, the second lens is a lens group; the lens group includes at least two lenses.

[0024] Optionally, the second lens includes two metalenses; or two refractive lenses.

[0025] Optionally, the second lens includes a metalens and a refractive lens.

[0026] The laser radar transmitting system provided in the embodiment of the present application has at least the following beneficial effects:

[0027] The laser radar transmitting system provided in the embodiment of the present application forms a mapping between the sub-light sources in the array of the light source and the sub-lens in the first lens, accurately modulates the sub-light sources, and compresses the total system length and working distance of the laser radar transmitting system through the first lens and the second lens including at least one super lens. The laser radar transmitting system also improves the collimation of the outgoing light through the first lens and the second lens, so that the divergence angle of the outgoing light passing through the laser radar transmitting system is less than 0.3°. By adopting the sub-lens array and the second lens, the embodiment of the present application makes the ratio of the total system length of the laser radar transmitting system to the equivalent focal length less than 0.5; the ratio of the working distance to the equivalent focal length is less than 0.1; and at the same time, the small system total length, small working distance and high collimation are satisfied; thereby promoting the miniaturization and lightweight of the laser radar transmitting system. The laser radar transmitting system provided in the embodiment of the present application has the advantages of light weight, small size, simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0029] Figure 1 An optional structural schematic diagram of a laser radar transmitting system provided in an embodiment of the present application is shown;

[0030] Figure 2 Another optional structural schematic diagram of the laser radar transmitting system provided in the embodiment of the present application is shown;

[0031] Figure 3 Another optional structural schematic diagram of the laser radar transmitting system provided in the embodiment of the present application is shown;

[0032] Figure 4 Another optional structural schematic diagram of the laser radar transmitting system provided in the embodiment of the present application is shown;

[0033] Figure 5 A schematic diagram showing a mapping of a sub-lens and a sub-light source provided in an embodiment of the present application is shown;

[0034] Figure 6 An optional structural schematic diagram of the nanostructure provided in the embodiment of the present application is shown;

[0035] Figure 7 Another optional structural schematic diagram of the nanostructure provided in the embodiment of the present application is shown;

[0036] Figure 8 An optional structural diagram of a superstructure unit provided in an embodiment of the present application is shown;

[0037] Fig. 9 Another optional structural diagram of the superstructure unit provided in the embodiment of the present application is shown;

[0038] Fig.10 Another optional structural diagram of the superstructure unit provided in the embodiment of the present application is shown;

[0039] Fig.11 A relationship diagram between transmittance and phase modulation of an optional nanostructure provided in an embodiment of the present application is shown.

[0040] The reference numerals in the figure represent respectively:

[0041] 100-first lens; 200-second lens; 300-third lens; 400-fourth lens;

[0042] 300 - Light source. DETAILED DESCRIPTION

[0043] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Furthermore, in the drawings, the thickness, ratio and size of the components are exaggerated for clarity.

[0044] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to another element and integrated therewith, or there may be an intermediate element at the same time. The terms "installed", "one end", "the other end" and similar expressions used herein are for illustrative purposes only.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The terms used herein are only for the purpose of describing specific embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, "one", "the", "at least one" as used herein do not represent a limitation on quantity, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, "a component" has the same meaning as "at least one component". "At least one" should not be interpreted as being limited to the quantity "one". The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0046] The meaning of “include” or “comprising” specifies properties, quantities, steps, operations, components, parts or a combination thereof, but does not exclude other properties, quantities, steps, operations, components, parts or a combination thereof.

[0047] Embodiments are described herein with reference to cross-sectional views as idealized embodiments. Thus, variations in shape relative to the illustrated diagram are anticipated as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as shown herein, but should include deviations in shape due to, for example, manufacturing. For example, a region shown or described as flat may typically have rough and / or nonlinear features. Moreover, the sharp angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims.

[0048] With the implementation of LiDAR in the consumer electronics and automotive electronics industries, its miniaturization and lightweighting has become an urgent problem to be solved. In particular, the size and weight of existing LiDARs are still difficult to meet the application requirements in fields such as drones. This application further realizes the miniaturization and lightweighting of LiDAR by compressing the size and weight of the LiDAR transmitting system, more specifically, by compressing the size and weight of the optical system in the LiDAR transmitting system.

[0049] In order to reduce the size of the LiDAR, it is necessary to minimize the total length (TTL) of the LiDAR transmitting system. The total length of the LiDAR receiving system refers to the distance from the center of the first optical element of the lens in the receiving system to the center of the focal plane along the incident direction. Therefore, the smaller the lens thickness, the fewer the number of lenses, and the shorter the focal length of the lens, the smaller the total length of the system.

[0050] The working distance (WD) of the LiDAR transmitting system refers to the distance from the light source surface to the first lens surface in the transmitting system along the emission direction. In addition to reducing the number of lenses, reducing the thickness of lenses, and shortening the distance between lenses, the volume of the LiDAR transmitting system can also be reduced by reducing the working distance. It should be noted that the smaller the working distance, the more conducive it is to the integration of the LiDAR transmitting system.

[0051] The collimation of the emitted light is one of the important indicators for evaluating the optical performance of the laser radar transmitting system. Compressing the volume of the laser radar transmitting system by reducing the total length and working distance of the system requires ensuring its optical performance. The existing laser radar transmitting system is generally composed of at least four groups of refractive lenses. This type of structure is difficult to simultaneously meet the requirements of small system length, small working distance and high collimation.

[0052] Therefore, there is an urgent need for a laser radar transmitting system that has the advantages of small system total length, small working distance and high collimation.

[0053] Figures 1 to 4 A laser radar transmitting system provided by an embodiment of the present application is shown. Figures 1 to 4 As shown, the laser radar transmitting system includes a first lens 100, a second lens 200 and a light source 300. Among them, the first lens 100 includes a plurality of arrays of sub-lenses 101. The light source 300 includes a plurality of arrays of sub-light sources 301. The first lens 100 and the second lens 200 are coaxial and are sequentially arranged on the light-emitting side of the light source 300. The sub-lens 101 and the sub-light source 301 are in a mapping relationship. After the light emitted by the light source 300 passes through the first lens 100 and the second lens 200 in sequence, the divergence angle is less than 0.3°.

[0054] According to the implementation mode of the present application, the sub-lens 101 can be a superlens or a microlens array (MLA). The microlens array is an array composed of lenses with a clear aperture and a relief depth of micrometers. Like a traditional lens, its smallest functional unit can also be a spherical mirror, an aspherical mirror, a cylindrical mirror, a prism, etc. It can also achieve focusing, imaging, beam transformation and other functions at a micro-optical angle, and because of its small unit size and high integration, it can constitute many new optical systems and complete functions that traditional optical elements cannot complete. Optionally, the sub-light source 301 is a laser light source, such as a vertical external cavity surface emitting laser (VECSEL).

[0055] According to the embodiment of the present application, the mapping relationship between the sub-light source 301 and the sub-lens 101 can be a one-to-many mapping, that is, one sub-lens 101 corresponds to multiple sub-light sources 301. It should be understood that the mapping relationship can also be a many-to-one mapping, that is, one sub-light source 301 corresponds to multiple sub-lenses 101. Preferably, Figure 5 As shown, the mapping relationship is a one-to-one mapping, that is, one sub-lens 101 is only responsible for modulating the light emitted by one sub-light source 301. It should be noted that many-to-many mapping is also feasible, that is, multiple sub-lenses 101 correspondingly modulate the light emitted by multiple sub-light sources 301. The embodiment of the present application is only illustrated by a one-to-one mapping structure.

[0056] Specifically, the ratio of the working distance (WD) of the laser radar transmitting system to the equivalent focal length (EFL, Effective Focal Length) is less than or equal to 0.1, that is, WD / FL≤0.1. The ratio of the total system length (TTL) of the laser radar transmitting system to the equivalent focal length (EFL, Effective Focal Length) is less than or equal to 0.5, that is, TTL / EFL≤0.5. The first lens 100 and the second lens 200 are arranged on the light-emitting side of the light source 300 in sequence with the same optical axis. Preferably, the working distance of the laser radar transmitting system is less than or equal to 8 mm. More preferably, the total system length of the laser radar transmitting system is less than or equal to 10 times the working distance.

[0057] like Figure 5 As shown, the first light emitted by each sub-light source 301 is modulated by its corresponding sub-lens 101 to form a second light beam. Figures 1 to 4 As shown, the second light is modulated or refracted by the second lens 200 to form a third light beam. The divergence angle of the first light beam, that is, the divergence angle of the sub-light source 301 is 2θ; the divergence angle of the second light beam, that is, the divergence angle of the sub-lens 101 is 2θ n ; The divergence angle of the third light is 2θ out .

[0058] In an optional implementation, to ensure that the light emitted by the light source 300 does not overlap on the first lens 100, the laser radar transmission system provided in the embodiment of the present application satisfies the following formula (1):

[0059] (1);

[0060] In formula (1), θ is the half divergence angle of the sub-light source 301; f MLA is the focal length of the sub-lens 101; D is the aperture of the sub-lens 101; 2 h is the diameter of the sub-light source 301; and P is the spacing between adjacent sub-light sources 301. When the cross section of the sub-light source 301 perpendicular to the optical axis is not circular, the diameter of the sub-light source 301 refers to the diameter of its circumscribed circle.

[0061] Further, according to an embodiment of the present application, optionally, in order to enable the first lens 100 to collimate the light emitted by the light source 300, the laser radar transmitting system satisfies the following formula (2):

[0062] (2);

[0063] In formula (2), 2θ n is the divergence angle of the second light after being collimated by the sub-lens 101; f MLAis the focal length of the sub-lens 101; h is the radius of the sub-light source 301.

[0064] According to the embodiment of the present application, more advantageously, the second lens 200 is located on the focal plane of the first lens 100, so that as much second light modulated by the first lens 100 as possible is incident on the second lens 200. The second lens 200 is preferably a monolithic metalens, but when the optical power of the monolithic metalens cannot meet the requirements, the number of lenses can be increased to form a lens group, so that the optical performance of the second lens 200 meets the requirements of the laser radar transmission system.

[0065] In some embodiments of the present application, Figure 1 As shown, the second lens 200 is a monolithic metalens. The divergence angle is 2θ n The second light is modulated by the periodically arranged nanostructures on the surface of the second lens 200 to form a divergence angle of 2θ. out The third light is the outgoing light of the laser radar transmitting system provided in the embodiment of the present application.

[0066] In some other embodiments of the present application, Figure 2 As shown, the second lens 200 is a single refractive lens. The divergence angle is 2θ n The second light is refracted by the second lens 200 to form a divergence angle of 2θ out The third light is the outgoing light of the laser radar transmitting system provided in the embodiment of the present application.

[0067] In some other embodiments of the present application, Figure 3 and Figure 4 As shown, the second lens 200 is a lens group, which includes at least two coaxially arranged lenses. Figure 3 As shown, the second lens 200 includes two metalenses; or, the second lens 200 includes a metalense and a refractive lens; or, the second lens 200 includes two refractive lenses.

[0068] It should be noted that the refractive lens mentioned in any of the above embodiments may be a single refractive lens. However, in practical applications, a refractive lens may be composed of a plurality of lenses with different curvatures.

[0069] Next, the superlens used in the embodiment of the present application is described. The superlens is a specific application of a supersurface, and the surface of the superlens has a periodically arranged nanostructure, and the characteristic size of the nanostructure is a subwavelength size. The characteristic size includes dimensions such as the diameter, circumference, and height of the nanostructure. The subwavelength size refers to a size that is less than or equal to the incident wavelength, or in some cases may be slightly larger than the incident wavelength. The superlens modulates the phase, amplitude, and polarization of the incident light through periodically arranged subwavelength-sized nanostructures.

[0070] Figure 6 and Figure 7 A perspective view of a nanostructure of a metalens used in a laser radar transmitting system provided in an embodiment of the present application is shown. Optionally, air or other materials that are transparent or translucent in the working band can be filled between the nanostructures on the metalens. According to an embodiment of the present application, the absolute value of the difference between the refractive index of the filled material and the refractive index of the nanostructure should be greater than or equal to 0.5. Figure 6 As shown in , nanostructures can be polarization-dependent structures that impose a geometric phase on incident light. Figure 7 As shown, nanostructures can be polarization-independent structures that impose a propagation phase on incident light.

[0071] According to an embodiment of the present application, the metalens includes a substrate and a microstructure layer disposed on the substrate, such as Figures 8 to 10 As shown, the microstructure layer includes superstructure units arranged in an array.

[0072] like Figure 8 As shown, according to the embodiment of the present application, the superstructure units can be arranged in a fan shape. Fig. 9 As shown, according to the embodiment of the present application, the superstructure units can be arranged in a regular hexagonal array. Fig.10 As shown, according to the embodiment of the present application, the superstructure units can be arranged in a square array. Those skilled in the art should recognize that the superstructure units included in the microstructure layer can also include other forms of array arrangements, and all these variations are included in the scope of the present application.

[0073] According to the embodiments of the present application, the superstructure unit may have a nanostructure. Figures 8 to 10As shown, according to an embodiment of the present application, a nanostructure is respectively arranged at the center position and / or the vertex position of each microstructure unit. According to an embodiment of the present application, the nanostructure is an all-medium structural unit. Optionally, the operating band of the superlens in the embodiment of the present application is a commonly used band of laser radar, including a near-infrared band, such as 850nm, 905nm, 940nm and 1550nm. According to an embodiment of the present application, the nanostructure has a high transmittance in the near-infrared light band. According to an embodiment of the present application, the nanostructure can be formed by at least one of the following materials: titanium oxide, silicon nitride, fused quartz, aluminum oxide, gallium nitride, gallium phosphide, amorphous silicon, crystalline silicon and hydrogenated amorphous silicon, etc.

[0074] The transmittance and phase modulation relationship of an optional nanostructure provided in the embodiment of the present application is as follows: Fig.11 shown. Fig.11 The figure shows the relationship between transmittance and phase modulation of 1200nm high silicon nanostructures arranged in a regular tetragon with a period of 600nm. Example 1

[0075] For example, the present application provides a laser radar transmission system, such as Figure 1 As shown, the system includes a first lens 100, a second lens 200 and a light source 300. The first lens 100 includes a plurality of sub-lenses 101, and the sub-lenses 101 are metalenses. The lens 200 includes two metalenses. The light source 300 includes a plurality of sub-light sources 301 arranged in an array. The key parameters of the laser radar transmission system are shown in Table 1, and the operating band is 1550nm.

[0076] Table 1

[0077]

[0078] As shown in Table 1, after the 200 μm light source 300 is collimated by the first lens 100 and the second lens 200 in the laser radar transmitting system provided in this embodiment, the divergence angle 2θ of the emitted light is out Less than 0.2°, meeting the requirements of the scanning laser radar transmitting system. The total length of the subsequent system in Table 1 refers to the distance from the incident surface of the first lens 100 to the exit surface of the second lens 200. The working distance of the subsequent system in Table 1 refers to the distance from the incident surface of the first lens 100 to the incident surface of the second lens 200. Example 2

[0079] For example, the present application provides a laser radar transmission system, such as Figure 4As shown, the laser radar transmitting system includes a first lens 100, a second lens 200 and a light source 300. Among them, the first lens 100 includes a plurality of sub-lenses 101, and the sub-lens 101 is a metalens. The lens 200 includes a metalens and a refractive lens. The light source 300 includes a plurality of sub-light sources 301 arranged in an array. The key parameters of the laser radar transmitting system are shown in Table 2, and the operating band is 1550nm.

[0080] Table 2

[0081]

[0082] As shown in Table 2, after the 200 μm light source 300 is collimated by the first lens 100 and the second lens 200 in the laser radar transmitting system provided in this embodiment, the divergence angle 2θ of the emitted light is out Less than 0.15°, meeting the requirements of scanning laser radar emission system.

[0083] It should be noted that, since the optical path is reversible, the optical system including at least one superlens in the laser radar transmitting system provided in the embodiment of the present application can be used in the laser radar receiving system.

[0084] The metalens used in the laser radar transmitting system provided in the embodiment of the present application can be mass-produced by semiconductor processing. Semiconductor processing can reduce the cost of the metalens and improve the mass production consistency of the metalens.

[0085] In summary, the laser radar transmitting system provided in the embodiment of the present application forms a mapping through the sub-light sources of the array in the light source and the sub-lens in the first lens, and the total system length and working distance of the laser radar transmitting system are compressed by the first lens and the second lens including at least one super lens. The laser radar transmitting system also improves the collimation of the outgoing light through the first lens and the second lens, so that the divergence angle of the outgoing light passing through the laser radar transmitting system is less than 0.3°. By adopting the sub-lens array and the second lens, the embodiment of the present application makes the ratio of the total system length of the laser radar transmitting system to the equivalent focal length less than 0.5; the ratio of the working distance to the equivalent focal length is less than 0.1; at the same time, the small system total length, small working distance and high collimation are satisfied; thereby promoting the miniaturization and lightweight of the laser radar transmitting system. The laser radar transmitting system provided in the embodiment of the present application has the advantages of light weight, small size, simple structure and low cost.

[0086] The above is only a specific implementation of the embodiment of the present application, but the protection scope of the embodiment of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the embodiment of the present application, which should be included in the protection scope of the embodiment of the present application. Therefore, the protection scope of the embodiment of the present application shall be based on the protection scope of the claims.

Claims

1. A laser radar transmitting system, characterized in that: The laser radar transmitting system comprises a first lens (100), a second lens (200) and a light source (300); Wherein, the first lens (100) comprises a plurality of arrayed sub-lenses (101); The light source (300) comprises a plurality of arrays of sub-light sources (301); The first lens (100) and the second lens (200) are coaxial and are sequentially arranged on the light-emitting side of the light source (300); The sub-lens (101) and the sub-light source (301) are in a mapping relationship; The ratio of the working distance to the equivalent focal length of the laser radar transmitting system is less than or equal to 0.

1.

2. The laser radar transmitting system according to claim 1, characterized in that: The sub-lens (101) is a super-lens or a micro-lens array.

3. The laser radar transmitting system according to claim 1, characterized in that: The sub-lens (101) and the sub-light source (301) are mapped one-to-one.

4. The laser radar transmitting system according to any one of claims 1 to 3, characterized in that: The ratio of the total system length of the laser radar transmitting system to the equivalent focal length is less than or equal to 0.

1.

5. The laser radar transmitting system according to any one of claims 1 to 3, characterized in that: The working distance of the laser radar transmitting system is less than or equal to 8 mm.

6. The laser radar transmitting system according to any one of claims 1 to 3, characterized in that: The total system length of the laser radar transmitting system is less than or equal to 10 times the working distance.

7. The laser radar transmitting system according to any one of claims 1 to 3, characterized in that: The laser radar transmitting system at least meets the following requirements: ； Wherein, θ is the half divergence angle of the sub-light source (301); f MLA is the focal length of the sub-lens (101); D is the aperture of the sub-lens (101); h is the diameter of the sub-light source (301); and P is the spacing between adjacent sub-light sources (301).

8. The laser radar transmitting system according to any one of claims 1 to 3, characterized in that: The laser radar transmitting system at least meets the following requirements: ； Among them, 2θ n is the divergence angle of the second light after being collimated by the sub-lens (101); f MLA is the focal length of the sub-lens (101); h is the radius of the sub-light source (301).

9. The laser radar transmitting system according to claim 1, characterized in that: The second lens (200) is a monolithic metalens.

10. The laser radar transmitting system according to claim 1, characterized in that: The second lens (200) is a lens group; the lens group comprises at least two lenses.

11. The laser radar transmitting system according to claim 1, characterized in that: The second lens (200) includes two metalenses; or two refractive lenses.

12. The laser radar transmitting system according to claim 1, characterized in that: The second lens (200) includes a metalens and a refractive lens.

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