CN115061114A

CN115061114A - Laser radar transmitting system, scanning method and wafer-level packaged device

Info

Publication number: CN115061114A
Application number: CN202210790343.7A
Authority: CN
Inventors: 郝成龙; 谭凤泽; 朱瑞; 朱健
Original assignee: Shenzhen Metalenx Technology Co Ltd
Current assignee: Shenzhen Metalenx Technology Co Ltd
Priority date: 2022-07-06
Filing date: 2022-07-06
Publication date: 2022-09-16

Abstract

The embodiment of the application provides a laser radar transmitting system, a scanning method and a wafer-level packaging device, and belongs to the technical field of laser radars. The system comprises: the first super lens array comprises first super lenses arranged in an array, and the first super lenses are Wheatstone super lenses; the light emitting array comprises light emitting units arranged in an array; the light emitting array is arranged on an object space focal plane of the first super lens array, and the light emitting unit is used for generating a first light beam; the first light beam is divergent laser with a principal ray parallel to the optical axis of the first super lens array; the diaphragm array comprises sub diaphragms arranged in an array; the diaphragm array is arranged on one side of the first super lens array far away from the light emitting array; the first light beam is converted into a second light beam through the first super lens array and is emitted from the diaphragm array; the second light beam is parallel light; wherein the relative position of the light emitting array and the first superlens array in a direction perpendicular to the optical axis is adjustable. The system has simple structure and promotes the miniaturization of the laser radar transmitting system.

Description

Laser radar transmitting system, scanning method and wafer-level packaged device

Technical Field

The present application relates to the field of lidar technology, and more particularly, to lidar transmission systems, scanning methods, and wafer level packaged devices.

Background

Lidar (Light Detection And Ranging) is a technology for detecting characteristic quantities such as a position, a velocity, And the like of an object by emitting laser Light And receiving a laser echo signal. The laser radar transmission system is one of the core components of the laser radar. In general, a lidar transmission system includes a laser light source and a corresponding optical system.

In a laser radar transmitting System in the prior art, a Micro Electro Mechanical System (MEMS) reflector is used to change the emitting angle of a laser beam so as to scan a far-field detection target by the laser beam. Lidar employing this design concept requires MEMS mirror dwell scanning, both one-dimensional and two-dimensional.

The scanning range of the laser radar transmitting system with the structure in the vertical direction depends on the number of laser paths, and the scanning angle in the horizontal direction depends on the scanning range of the MEMS reflecting mirror. Namely, the scanning range in the vertical direction is larger as the number of laser paths is larger; the angle of the MEMS reflector changes by a certain value, and the scanning angle of the laser changes by a certain value correspondingly.

However, due to the existence of the MEMS mirror, the structure and the optical path of the structure are complicated, and the cost is high, so that the structure is difficult to meet the increasingly severe requirements of the market on miniaturization, light weight, simplification and low cost of the laser radar.

Disclosure of Invention

In order to solve the problem that the scanning range of a laser radar transmitting system is limited by an MEMS (micro-electromechanical system) reflecting galvanometer in the prior art, the embodiment of the application provides the laser radar transmitting system, a scanning method and a wafer-level packaged device.

In a first aspect, an embodiment of the present application provides a laser radar transmission system, where the system includes:

the first super lens array comprises at least one first super lens arranged in an array, and the first super lens is a Wheatstone super lens;

the light emitting array comprises at least one light emitting unit arranged in an array; the light emitting array is arranged on an object focal plane of the first super lens array, and the light emitting unit is used for generating a first light beam; the first light beam is divergent laser with a principal ray parallel to the optical axis of the first super lens array;

the diaphragm array comprises at least one array of sub diaphragms; the diaphragm array is arranged on one side of the first superlens array far away from the light emitting array; the first light beam is converted into a second light beam through the first super lens array and is emitted from the diaphragm array; the second light beam is parallel light;

wherein the relative positions of the light emitting array and the first superlens array in a direction perpendicular to the optical axis are adjustable.

Optionally, the system further satisfies:

Δθ＝arctan(Δd/L)；

wherein Δ d is a relative displacement of the first superlens array and the light emitting array in a direction perpendicular to the optical axis; l is the distance between the diaphragm array and the first super lens array; and delta theta is the rotating angle of the second light beam after the first super lens array and the light emitting array generate relative displacement in the direction vertical to the optical axis.

Optionally, the light emitting unit includes a point light source and a focal point of the converged laser light;

the converging laser forms the first beam after passing through the focal point.

Optionally, the system further comprises an array of converging devices; the convergence device array comprises at least one array of sub-convergence devices; the converging device array is arranged at the upstream of the first super lens array and is used for converging the incident laser to at least one focus;

the sub-converging means comprises a spherical refractive lens, an aspherical refractive lens or a second superlens.

Optionally, the system further comprises a microelectromechanical system; the micro-electro-mechanical system is configured to adjust a displacement of the light emitting array and/or the first superlens array in a direction perpendicular to the optical axis.

Optionally, the drive stroke of the mems is less than or equal to 10 mm.

Optionally, the driving accuracy of the mems is greater than or equal to 1 micron and less than or equal to 5 microns.

Optionally, the operating frequency of the microelectromechanical system is greater than 1 kHz.

Optionally, the system further comprises a wavefront modifier; the wavefront modulator is disposed at an entrance pupil of the array of converging devices;

the wavefront modifier is used to adjust the focal position of the array of converging devices.

Optionally, the wavefront modulator comprises a spatial light modulator, a digital micro-mirror array, a tunable super-surface spatial light modulator.

Optionally, the first superlens and the second superlens each comprise a substrate and a nanostructure layer disposed on the substrate;

the nanostructure layer comprises nanostructures arranged in an array.

Optionally, the nanostructure layer comprises superstructure units arranged in an array;

the superstructure unit is a close-stackable pattern; the center position and/or the vertex position of the close-packable pattern is provided with the nano-structure.

Optionally, the superlens further comprises a filler material;

the filling material is filled between the nano structures.

Optionally, an absolute value of a difference between the refractive index of the filler material and the refractive index of the nanostructures is greater than or equal to 0.5.

Optionally, the period of the superstructure unit is greater than or equal to 0.3 λ _c And is less than or equal to 2 lambda _c ；

Wherein λ is _c Is the center wavelength of the operating band of the system.

Optionally, the height of the nanostructures is greater than or equal to 0.3 λ _c And is less than or equal to 5 lambda _c ；

Wherein λ is _c Is the center wavelength of the operating band of the system.

Optionally, the shape of the nanostructure comprises a polarization sensitive structure.

Optionally, the shape of the nanostructure comprises a polarization insensitive structure.

Optionally, the superlens further comprises an antireflection film;

the antireflection film is arranged on one side of the substrate and the side, adjacent to the air, of the nanostructure layer.

Optionally, the phase of the first superlens at least satisfies:

wherein r is the distance from the center of the first superlens to the center of any of the nanostructures; lambda is the wavelength of operation and,

and x and y are the mirror coordinates of the first super lens, and f is the focal length of the first super lens.

In a second aspect, an embodiment of the present application further provides a laser radar scanning method, which is suitable for the laser radar transmitting system provided in any of the above embodiments, where the method includes:

arranging the light emitting array, the first super lens array and the diaphragm array in sequence along the laser emergent direction; the first light beam generated by the light emitting array is converted into a second light beam through the first super lens array and is emitted out of the sub-diaphragm; the first light beam is divergent laser with a principal ray parallel to the optical axis of the first super lens; the second light beam is parallel light;

and adjusting the relative positions of the light emitting array and the first super lens array in the direction vertical to the optical axis so as to rotate the emergent angle of the second light beam.

Optionally, the relative position satisfies:

Δx＝L tan(θ _x )；

Δz＝L tan(θ _z )；

wherein x is a first direction perpendicular to the optical axis, z is a second direction perpendicular to the optical axis, and the x direction is perpendicular to the z direction; l is the distance between the diaphragm array and the first super lens array; and theta is the rotation angle of the second light beam emitted by the diaphragm array.

Optionally, the light emitting array, the first superlens array and the diaphragm array are two-dimensional arrays;

and adjusting the relative positions of the light emitting array and the first superlens array in a direction perpendicular to the optical axis so as to rotate the second light beam in a two-dimensional scanning manner.

Optionally, the light emitting array, the first superlens array, and the diaphragm array are all one-dimensional arrays;

and adjusting the relative positions of the light emitting array and the first superlens array in the direction perpendicular to the optical axis so as to rotate the second light beam in a one-dimensional scanning mode.

In a third aspect, an embodiment of the present application further provides a wafer level packaged device, which is suitable for the laser radar transmitting system provided in any of the above embodiments, where the wafer level packaged device includes:

the light emitting array comprises a light source array which is arranged on a focal plane of the converging device array; and

a first spacing layer disposed between the array of converging devices and the array of light sources, the first spacing layer having a height equal to a focal length of the array of converging devices;

the first super lens array is arranged on one side of the converging device array, which is far away from the light source array; and the object focal plane of the first superlens array coincides with the focal plane of the converging device array;

the second spacing side is arranged on one side, away from the converging device array, of the first super lens array and is used for supporting the diaphragm array;

and the light emitting array and/or the first superlens array are arranged on a displacement platform so as to realize the relative displacement of the light emitting array and the first superlens array.

The laser radar transmitting system provided by the embodiment of the application forms an object space telecentric system by the first super lens array and the diaphragm array, and realizes deflection of the second light beam by means of relative displacement of the light emitting array and the first super lens array in the direction vertical to the optical axis. The system omits an MEMS reflecting vibrating mirror, has a simple structure and a concise light path, and is beneficial to the miniaturization and the light weight of a laser radar transmitting system.

Drawings

The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

Fig. 1 is a schematic diagram illustrating an alternative structure of a lidar transmitting system provided by an embodiment of the present application;

FIG. 2 is a schematic diagram illustrating an alternative structure of a lidar transmission system provided by an embodiment of the present application;

FIG. 3 is a schematic diagram illustrating an alternative structure of a lidar transmission system provided by an embodiment of the present application;

FIG. 4 is a schematic diagram illustrating an alternative structure of a lidar transmission system provided by an embodiment of the present application;

FIG. 5 is a schematic diagram illustrating an alternative structure of a lidar transmission system provided by an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating an alternative structure of a sub-convergence device provided in the embodiments of the present application;

FIG. 7 is a schematic diagram illustrating an alternative structure of a sub-convergence device provided in the embodiment of the present application;

fig. 8 is a schematic structural diagram illustrating yet another alternative sub-convergence device provided in the embodiment of the present application;

FIG. 9 is a schematic diagram illustrating an alternative structure of a sub-convergence device provided in the embodiment of the present application;

FIG. 10 is a schematic diagram of an alternative arrangement of a superlens provided by an embodiment of the present application;

FIG. 11 illustrates an alternative structural schematic of a nanostructure provided by an embodiment of the present application;

FIG. 12 shows a schematic diagram of yet another alternative structure of a nanostructure provided by an embodiment of the present application;

FIG. 13 shows an alternative structural schematic of a superstructure unit provided by embodiments of the present application;

FIG. 14 is a schematic diagram illustrating an alternative structure of a superstructure unit provided by embodiments of the present application;

FIG. 15 shows a schematic diagram of yet another alternative structure of a superstructure unit provided by embodiments of the present application;

FIG. 16 is a graph showing transmittance versus phase modulation for an alternative nanostructure provided by an embodiment of the present application;

FIG. 17 is a schematic diagram illustrating an alternative laser radar scanning method provided in an embodiment of the present application;

FIG. 18 is a schematic diagram illustrating yet another alternative lidar scanning method provided by an embodiment of the present application;

FIG. 19 is a schematic diagram illustrating an alternative structure of a wafer level packaged device according to an embodiment of the present disclosure;

fig. 20 is a schematic diagram illustrating an alternative structure of a wafer-level packaged device according to an embodiment of the present disclosure;

FIG. 21 shows an alternative phase diagram for a spatial light modulator provided by an embodiment of the present application;

fig. 22 shows a further alternative phase diagram of the spatial light modulator provided by the embodiment of the present application.

The reference numerals in the drawings denote:

10-a first superlens array; 20-a light emitting array; 30-an array of diaphragms; 40-an array of converging means; 50-wavefront modulator; 60-adjustable focus optical system;

101-a first superlens; 201-a light emitting unit; 301-sub-diaphragm; 401-sub convergence device.

Detailed Description

The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like parts throughout. Also, in the drawings, the thickness, ratio and size of the components are exaggerated for clarity of illustration.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," "the," and "at least one" do not denote a limitation of quantity, but rather are intended to include both the singular and the plural, unless the context clearly dictates otherwise. For example, "a component" means the same as "at least one component" unless the context clearly dictates otherwise. "at least one of" should not be construed as limited to the quantity "one". "or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.

Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meaning as is in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The meaning of "comprising" or "comprises" indicates a property, a quantity, a step, an operation, a component, a part, or a combination thereof, but does not exclude other properties, quantities, steps, operations, components, parts, or combinations thereof.

Embodiments are described herein with reference to cross-sectional views that are idealized embodiments. Thus, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, regions shown or described as flat may typically have rough and/or nonlinear features. Also, the acute angles shown may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.

Hereinafter, exemplary embodiments according to the present application will be described with reference to the accompanying drawings.

The present embodiment provides a lidar transmission system, as shown in fig. 1 to 5, including a first superlens array 10, a light-emitting array 20, and a diaphragm array 30.

Wherein, the light emitting array 20 is disposed at one side of the first superlens array 10, and the diaphragm array 30 is disposed at the other side of the first superlens array 10, and the relative positions of the light emitting array 20 and the first superlens array 10 in the direction perpendicular to the optical axis are adjustable.

Specifically, the diaphragm array 30 is located in the image space of the first superlens array 10 and is arranged coaxially with the first superlens array 10 to constitute an object-side telecentric system. The first light beam generated by the light emitting array 20 is modulated by the first super lens array 10 to form a second light beam, and the second light beam is emitted from the diaphragm array 30. The first beam is a divergent laser whose chief ray is parallel to the optical axis of the first superlens array 10. The second light beam is parallel light. Optionally, the distance between the diaphragm array 30 and the first superlens array 10 is less than or equal to one focal length of the first superlens array 10.

Referring to fig. 2, due to the characteristics of the telecentric system, if the light emitting array 20, the first superlens array 10 and the diaphragm array 30 are disposed on the same optical axis, the second light beam is parallel to the optical axis of the first superlens array 10; if the optical axes of the light emitting array 20 and the first superlens array 10 are not coincident, the second light beam is deflected. For example, when the first superlens array 10 is not moved and the light emitting array 20 is displaced in any direction perpendicular to the optical axis of the first superlens array 10, the second light beam is deflected in a direction opposite to the displacement direction. For another example, when the light emitting array 20 is not moved and the combined body of the first superlens array 10 and the diaphragm array 30 is displaced in any direction perpendicular to the optical axis of the light emitting array 20, the second light beam is deflected in the same direction as the displacement. The second light beam is deflected by adjusting the relative displacement of the light emitting array 20 and the first superlens array 10 in the direction perpendicular to the optical axis, so that the second light beam is swept.

It should be noted that, in order to ensure the parallelism of the second light beam, the chief ray of the first light beam needs to be parallel to the optical axis direction of the first superlens array 10.

According to the embodiment of the application, optionally, the laser radar transmitting system further satisfies:

Δθ＝arctan(Δd/L)； (1)

in formula (1), Δ d is the relative displacement of the first superlens array 10 and the light emitting array 20 in the direction perpendicular to the optical axis; l is the distance between the diaphragm array 30 and the first superlens array 10; Δ θ is the rotation angle of the second light beam after the relative displacement between the first superlens array 10 and the light emitting array 20 in the direction perpendicular to the optical axis.

According to the embodiment of the present application, as shown in fig. 1 to 5, the first superlens array 10 includes at least one first superlens 101 arranged in an array, and the first superlens 101 is a huygens superlens. The huygens super lens is a super lens based on huygens equivalent principle and is characterized in that the included angle between the chief ray angle and the optical axis is less than or equal to 8 degrees. By designing the phase of the huygens superlens, the incident beam can be deflected in a predetermined manner. According to the embodiment of the present application, as shown in fig. 2, the first light beam is modulated by the first superlens 101 to form the second light beam. According to the embodiment of the present application, the light emitting array 20 includes at least one light emitting unit 201 arranged in an array. The light emitting array 20 is disposed on the object focal plane of the first superlens array 10. The light emitting array 20 is used to generate a first light beam. Alternatively, the light emitting unit 201 includes a point light source and a focus of converging laser light. Preferably, the light emitting unit 201 employs a focal point of the condensed laser light. According to the embodiment of the present application, the stop array 30 includes at least one sub-stop 301 arranged in an array. Preferably, the sub-diaphragms 301 and the first superlenses 101 are in one-to-one correspondence, so that any one first superlens 101 and the corresponding sub-diaphragm 301 constitute an object-side telecentric system.

According to the embodiment of the present application, as shown in fig. 3 and 4, when the light emitting unit 201 is a focal point of the condensed laser light, the laser radar transmission system further includes a condensing device array 40. The converging device array 40 includes at least one sub-converging device 401 arranged in an array. The converging device array 40 is used to converge parallel or approximately parallel laser light generated by the laser light source to a focal point to form the light emitting array 20. The convergent laser light forms a divergent first light beam after passing through a focus. Preferably, the focal point of the converging laser light is located on the object focal plane of the first superlens array 10.

According to an embodiment of the present application, as shown in FIG. 3, the array of converging means 40 is an array of refractive lenses. In some embodiments, the refractive lens is a spherical lens. Preferably, since the aspherical lens has better spherical aberration control than the spherical lens, the condensing device array 40 employs an aspherical refractive lens to reduce the spot size of the focal point as much as possible.

According to an embodiment of the present application, as shown in FIG. 4, the array of converging means 40 comprises a second superlens arranged in an array. Any second superlens can focus the incident parallel light onto the object focal plane of the corresponding first superlens 101 without spherical aberration. Compared with a refractive lens, the second super lens is smaller in thickness and free of spherical aberration.

In any of the above embodiments, the relative displacement of the light emitting array 20 and the first superlens array 10 is provided by a Micro-Electro-Mechanical System (MEMS) configured to adjust the displacement of the light emitting array 20 and/or the first superlens array 10 in a direction perpendicular to the optical axis. Illustratively, the microelectromechanical system includes a MEMS flexible suspension. A MEMS flexible suspension is coupled to the converging device array 40, the point light source or the first superlens array 10, the MEMS flexible suspension being configured to elastically deform in a direction perpendicular to the optical axis. Illustratively, the drive stroke of the MEMS is less than or equal to 10 millimeters. Preferably, the precision of the drive of the micro-electromechanical system is greater than or equal to 1 micron and less than or equal to 5 microns. Optionally, the operating frequency of the micro-electromechanical system is greater than 1 kHz.

Further, as shown in fig. 6 to 9, the lidar transmission system provided by the embodiment of the present application further includes a wavefront controller 50. The wavefront modifier 50 is disposed at the entrance pupil of the converging device array 40 for adjusting the focal position of the converging device array 40. As shown in FIG. 5, the array of converging means 40 and wavefront modifier 50 comprise an adjustable focus optical system.

Alternatively, the wavefront Modulator 50 includes an array of Spatial Light Modulators (SLM), a Digital Micromirror array (DMD), or a tunable super-surface Spatial Light Modulator (fsslm). Alternatively, the wavefront modifier may be a unit corresponding to a plurality of sub-converging means. Optionally, the wavefront modifiers are in the form of an array, wherein each wavefront modifying element is mapped one-to-many with a sub-converging device 401 in the converging device array 40. Optionally, the wavefront modifiers are in the form of an array, wherein each wavefront modifying element is mapped one-to-one with a sub-converging device 401 in the converging device array 40.

According to an embodiment of the present application, as shown in fig. 6, the sub-converging device 401 is a microscope objective, and the wavefront modifier 50 is located at the entrance pupil of the microscope objective. Alternatively, referring to fig. 7, the sub-converging means 401 is a lens group of refractive lenses, and the wavefront modulator 50 is located at the entrance pupil of the lens group. In some exemplary embodiments, the sub-converging device 401 is a second superlens. In still other exemplary embodiments, the sub-converging means 401 is a combination of a second superlens and a refractive lens.

Next, the first superlens and the second superlens provided in the embodiments of the present application are described in detail with reference to fig. 10 to 16. A superlens is a specific application of a supersurface that modulates the phase, amplitude and polarization of incident light by periodically arranged sub-wavelength-sized nanostructures.

FIG. 10 is a schematic diagram illustrating an alternative structure of a superlens provided by an embodiment of the present application. Referring to fig. 10, the first superlens and the second superlens each include a base layer and a nanostructure layer disposed on the base layer. Wherein the nanostructure layer comprises periodically arranged nanostructures.

According to an embodiment of the present application, optionally, in the nanostructure layer, the arrangement period of the nanostructures is greater than or equal to 0.3 λ _c And is less than or equal toIs equal to 2 lambda _c (ii) a Wherein λ is _c The center wavelength of the operating band.

According to embodiments of the present application, optionally, the height of the nanostructures in the nanostructure layer is greater than or equal to 0.3 λ _c And is less than or equal to 5 lambda _c (ii) a Wherein λ is _c The center wavelength of the operating band.

Fig. 11 and 12 show perspective views of nanostructures in a superlens. Alternatively, the nanostructures in fig. 11 are cylindrical structures. Alternatively, the nanostructure in fig. 12 is a square pillar structure. Optionally, as shown in fig. 11 and 12, the superlens further includes a filler, the filler is filled between the nano-structures, and an extinction coefficient of a material of the filler to the operating band is less than 0.01. Optionally, the filler comprises air or other material that is transparent or translucent in the operating band. According to an embodiment of the present application, the absolute value of the difference between the refractive index of the material of the filler and the refractive index of the nanostructures should be greater than or equal to 0.5.

In some alternative embodiments of the present application, as shown in fig. 13 to 15, the nanostructure layer includes superstructure units arranged in an array. The superstructure unit is a close-packable graph, and a nano structure is arranged at the vertex and/or the center of the close-packable graph. In the embodiments of the present application, the close-packable patterns refer to one or more patterns that can fill the entire plane without gaps and without overlapping.

As shown in fig. 13, according to an embodiment of the present application, the superstructure units may be arranged in a fan shape. As shown in fig. 14, according to an embodiment of the present application, the superstructure units may be arranged in an array of regular hexagons. Further, as shown in fig. 15, according to an embodiment of the present application, the superstructure units may be arranged in a square array. Those skilled in the art will recognize that the superstructure units included in the nanostructure layer may also include other forms of array arrangements, and all such variations are contemplated within the scope of the present application.

Illustratively, the nanostructures provided by the embodiments of the present application may be polarization-independent structures, which impose a propagation phase on incident light. According to embodiments of the present application, the nanostructures may be positive structures or negative structures. For example, the shape of the nanostructures includes cylinders, hollow cylinders, square prisms, hollow square prisms, and the like.

Exemplary shapes of the nanostructures include cylinders, hollow cylinders, square pillars, and hollow square pillars. Optionally, the nanostructure is disposed in a central position of the superstructure unit. In alternative embodiments of the present application, the shapes of the nanostructures include cylinders, hollow cylinders, square pillars, and hollow square pillars. Optionally, the nanostructure is disposed in a central location of the superstructure unit.

According to embodiments of the present application, the shape of the nanostructure includes a cylinder, a hollow cylinder, a square column, and a hollow square column. Optionally, the nanostructure is a negative nanostructure, such as a square pore column, a circular pore column, a square ring column, and a circular ring column.

In an alternative implementation, as shown in fig. 10, the superlens provided in the example of the present application further includes an antireflection film. The antireflection film is arranged on one side of the substrate layer away from the nanostructure layer; alternatively, the antireflection film is disposed on a side of the nanostructure layer adjacent to air. The antireflection film plays a role in antireflection and reflection reduction on incident radiation.

According to an embodiment of the present application, the material of the nanostructure is a material having an extinction coefficient of less than 0.01 with respect to the operating band. For example, nanostructured materials include fused silica, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon. For another example, when the operating wavelength band of the superlens is the near-infrared wavelength band, the material of the nanostructure includes one or more of silicon nitride, titanium oxide, gallium nitride, gallium phosphide, hydrogenated amorphous silicon, and crystalline silicon. For another example, when the working wavelength band of the superlens is visible light, the material of the nano-structure includes fused silica, quartz glass, crown glass, flint glass, sapphire and alkali glass. For another example, when the operating wavelength band of the superlens is the far infrared wavelength band, the material of the nanostructure includes one or more of crystalline silicon, crystalline germanium, zinc sulfide and zinc selenide.

For example, the material of the substrate layer includes fused silica, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon. For another example, when the operating wavelength band of the superlens is the near infrared wavelength band, the material of the substrate layer includes one or more of silicon nitride, titanium oxide, gallium nitride, gallium phosphide, hydrogenated amorphous silicon, and crystalline silicon. As another example, when the working wavelength band of the superlens is the visible wavelength band, the material of the substrate layer includes fused silica, quartz glass, crown glass, flint glass, sapphire, and alkali glass. For another example, when the operating wavelength band of the superlens is the far infrared wavelength band, the material of the substrate layer includes one or more of crystalline silicon, crystalline germanium, zinc sulfide, and zinc selenide.

In some embodiments of the present application, the material of the nanostructures is the same as the material of the substrate layer. In still other embodiments of the present application, the material of the nanostructures is different from the material of the substrate layer. Optionally, the material of the filler is the same as the material of the base layer. Optionally, the material of the filler is different from the material of the base layer.

It should be understood that in yet other alternative embodiments of the present application, the filler is of a different material than the nanostructures. Illustratively, the material of the filler is a high-transmittance material with an operating band, and the extinction coefficient of the high-transmittance material is less than 0.01. Exemplary materials for the filler include fused silica, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon.

According to the embodiment of the present application, the phase of each first superlens 101 in the first superlens array 10 satisfies at least one of the following equations (2-1) to (2-6):

wherein r is the distance from the center of the first superlens 101 to the center of any of the nanostructures; lambda is the wavelength of operation and,

x, y are the mirror coordinates of the first superlens, and f is the focal length of the first superlens, for any phase associated with the operating wavelength.

The phase of the superlens may be expressed by higher order polynomials including odd and even polynomials. In order not to destroy the rotational symmetry of the phase of the superlens, the phase corresponding to the even-order polynomial can be optimized, which greatly reduces the degree of freedom of the design of the superlens. In the formulas (2-1) to (2-6), compared with the other formulas (2-3) and (2-4), the phase satisfying the odd polynomial can be optimized without destroying the rotational symmetry of the phase of the superlens, so that the optimization degree of freedom of the superlens is greatly improved.

Fig. 16 shows transmittance, phase and nanostructure size of an alternative nanostructure provided by an embodiment of the present application. When the cylindrical nanostructure is selected, as shown in fig. 6, the diameter of the nano-pillars may be appropriately selected according to the transmittance and phase required for the design.

Second aspect an embodiment of the present application further provides a lidar scanning method, as shown in fig. 17 and fig. 18, which is applicable to the lidar transmitting system provided in any of the above embodiments. The method comprises the following steps:

arranging the light emitting array 20, the first superlens array 10 and the diaphragm array 30 in sequence along the laser emergent direction; the first light beam generated by the light emitting array 20 is converted into a second light beam by the first super lens array 10 and is emitted from the diaphragm array 30; the first light beam is divergent laser with a principal ray parallel to the optical axis of the first superlens array 10; the second light beam is parallel light;

the relative positions of the light emitting array 20 and the first superlens array 10 in the direction perpendicular to the optical axis are adjusted to rotate the exit angle of the second light beam.

According to an embodiment of the present application, the method is a two-dimensional array scan, as shown in fig. 17. Illustratively, as shown in FIG. 17, the light emitting array 20, the first superlens array 10, and the stop array 30 are two-dimensional arrays such that the second light beam forms a two-dimensional lattice in the far field. The two-dimensional array of second light beams is moved within the field of view by adjusting the relative positions of the light emitting array 20 and the first superlens array 10. For example, FIG. 17 shows a schematic view of a two-dimensional array performing a full field of view scan in a zig-zag scan within the field of view. Theta in FIG. 17 _H Representing the angle of rotation, theta, of the second beam in the horizontal direction _V Indicating the angle of rotation of the second beam in the vertical direction. According to an embodiment of the present application, the method wherein the relative position of the light emitting array 20 and the first superlens array 10 satisfies equation (1).

In yet another alternative embodiment, the method is a one-dimensional array scan, as shown in fig. 18. Illustratively, as shown in fig. 18, the light emitting array 20, the first superlens array 10, and the diaphragm array 30 are one-dimensional arrays such that the second beam forming can cover θ in the vertical direction _V A one-dimensional array of (a). By controlling the relative displacement of the light emitting array 20 and the first superlens array 10 in the horizontal direction, the one-dimensional array of the second light beams is deflected in the horizontal direction and covers theta _H Thereby realizing full-field scanning. Based on a similar principle, the second light beam is made to cover theta in the horizontal direction _H By adjusting the light emitting array 20 and the first superlens array 10 in the vertical directionThe full field of view scanning can also be realized by the relative displacement of the two parts.

In this method, the relative positions of the light emitting array 20 and the first superlens array 10 in the direction perpendicular to the optical axis satisfy:

Δx＝L tan(θ _x )； (3-1)

Δz＝L tan(θ _z )； (3-2)

wherein x is a first direction perpendicular to the optical axis, z is a second direction perpendicular to the optical axis, and the x direction is perpendicular to the z direction; l is the distance between the diaphragm array 30 and the first superlens array 10; θ is the rotation angle of the second light beam exiting through the aperture array 30.

In any of the above methods, accurate and high-speed scanning can be achieved by one-dimensional and/or two-dimensional MEMS actuators or displacement actuators and other electronic control devices.

It should be noted that the superlens provided by the embodiment of the present application can be processed by a semiconductor process, and has the advantages of light weight, thin thickness, simple structure and process, low cost, high consistency of mass production, and the like. In view of this, the embodiment of the present application further provides a wafer level packaged device.

In an alternative embodiment, referring to fig. 19 and 20, the wafer level packaged device wherein the light emitting array 20 is a focal array formed by focusing light from the light source array by the converging device array 40. Alternatively, the light source array includes a Vertical Cavity Surface Emitting Laser (VCSEL) and an Edge Emitting Laser (EEL). As shown in fig. 19 and 20, the array of converging means 40 is a second superlens array. The light source array is arranged on the wafer base, and the second super lens array is supported by the first spacing layer to form a first combination. The height of the first spacer layer is equal to the focal length of the second superlens. Preferably, the first spacer layer is opaque to the operating band. Preferably, the single light sources in the light source array are in one-to-one correspondence with the single superlenses in the second superlens array, and the light sources are located at the focal points of the second superlenses.

As shown in fig. 19 and 20, the stop array 30 is connected to the first superlens array 10 via a second spacer layer to form a second assembly. The second combination body and the first combination body are mutually independent, and the first super lens array is positioned on one side of the focal point array far away from the second super lens array.

The first combination and/or the second combination are disposed on the displacement platform, and the displacement platform realizes relative displacement between the first combination and the second combination, so that the first superlens array 10 and the light emitting array (i.e. the focus array) generate relative displacement.

Example 1

Embodiment 1 provides a 2x2 lidar transmission system with an operating band at 1550 nm. The first superlens array is an array of 2x2, the light emitting array is a converging laser focus array of 2x2, the stop array 30 is correspondingly an array of 2x2, and the distance of the stop array 30 from the first superlens array 10 is 2 mm. Wherein the half field angle of the single first superlens is 42 degrees, the focal length is 2mm, and the diameter is 3.6 mm. The field range to be scanned is preset to be 80 degrees multiplied by 30 degrees, so that in the laser radar transmitting system, the maximum emergent half field angle of the transmitting unit consisting of the single light-emitting unit, the single first super lens and the single diaphragm is 41.4 degrees so as to cover the field range to be scanned. The relative displacement between the light emitting array 20 and the first superlens array 10 in the lidar transmission system, the corresponding exit angle of the second light beam, and the parallelism of the second light beam are shown in table 1. In table 1, the y-axis is the optical axis, and the x-axis and the z-axis are two directions perpendicular to the optical axis, respectively. x is the horizontal direction and z is the vertical direction.

TABLE 1

Example 2

Embodiment 2 provides a 1x31 one-dimensional column scanning lidar transmission system with an operating band at 1550 nm. Wherein the parameters of the single first superlens are the same as those of the first superlens in embodiment 1. The lidar transmission system in example 2 is such that the angle between the optical axes of two adjacent light-emitting units is set to 1 ° in advance according to equations (3-1) and (3-2) in the manner shown in fig. 18. An angle point is preset 801 in the z direction, and two adjacent angle points are separated by 0.1 degrees. The laser radar transmitting system has the scanning times of more than 48060 times/second according to the depth image imaging frequency of 60 images per second, and the motion frequency of the corresponding one-dimensional nano displacement platform is 48.06 Hz.

Example 3

Embodiment 3 provides a lidar transmission system with an operating band at 1550 nm. The lidar transmission system further comprises a wavefront modifier 50. The parameters of a single first superlens in this system are shown in example 1. In the converging device array 40 matched with the wavefront regulator 50, the entrance pupil diameter of any sub-converging device 401 is 5mm, the focal length is 10mm, the object space field is 4mm, and the focusing is good at 1550 nm.

According to an embodiment of the present application, the wavefront modifier is located at an entrance pupil of the focusing optical system, wherein the relationship between the adjustable focus position and the phase at the entrance pupil is shown in equation (4):

in the formula, a _i And b _i Respectively the coordinates of the ith point in the x-z plane.

Fig. 21 and 22 show the phases of the wavefront modifier 50 at the entrance pupil of the sub-condensing device array 401 at the second beam deflection angles of (0 ° ) and (40 °, 15 °) in embodiment 3, respectively. Wherein (0 ° ) respectively denote that the second light beam is deflected by 0 ° in a horizontal direction perpendicular to the optical axis and by 0 ° in a vertical direction perpendicular to the optical axis; (40 °, 15 °) respectively indicate that the second light beam is deflected by 0 ° in the horizontal direction perpendicular to the optical axis and by 0 ° in the vertical direction perpendicular to the optical axis.

In summary, the laser radar transmitting system provided in the embodiment of the present application constitutes an object-side telecentric system by the first superlens array and the diaphragm array, and realizes the deflection of the second light beam by virtue of the relative displacement of the light emitting array and the first superlens array in the direction perpendicular to the optical axis. The system omits an MEMS reflecting vibrating mirror, has a simple structure and a concise light path, and is beneficial to the miniaturization and the light weight of a laser radar transmitting system.

The above description is only a specific implementation of the embodiments of the present application, but the scope of the embodiments of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the embodiments disclosed in the present application, and all the changes or substitutions should be covered by the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.

Claims

1. A lidar transmission system, the system comprising:

a first superlens array (10) comprising at least one first superlens (101) arranged in an array, wherein the first superlens (101) is a huygens superlens;

the light emitting array (20) comprises at least one light emitting unit (201) arranged in an array; the light emitting array (20) is arranged on an object focal plane of the first superlens array (10), and the light emitting unit (201) is used for generating a first light beam; the first light beam is divergent laser with a principal ray parallel to the optical axis of the first super lens array (10);

the diaphragm array (30) comprises at least one array of sub diaphragms (301); the diaphragm array (30) is arranged on the side of the first superlens array (10) far away from the light emitting array (20); the first light beam is converted into a second light beam through the first super lens array (10) and is emitted from the diaphragm array (30); the second light beam is parallel light;

wherein the relative position of the light emitting array (20) and the first superlens array (10) in a direction perpendicular to the optical axis is adjustable.

2. The system of claim 1, wherein the system is further adapted to:

Δθ＝arctan(Δd/L)；

wherein Δ d is the relative displacement of the first superlens array (10) and the light emitting array (20) in a direction perpendicular to the optical axis; l is the distance between the diaphragm array (30) and the first super lens array (10); delta theta is the rotation angle of the second light beam after the first super lens array (10) and the light emitting array (20) are subjected to relative displacement in the direction perpendicular to the optical axis.

3. The system according to claim 1, wherein the light emitting unit (201) comprises a point light source and a focal point of a converging laser light;

4. The system of claim 3, further comprising an array of converging means (40); the convergence device array (40) comprises at least one sub convergence device (401) arranged in an array; said array of converging means (40) being arranged upstream of said first superlens array (10) for converging incident laser light to at least one of said focal points;

the sub-converging means (401) comprises a spherical refractive lens, an aspherical refractive lens or a second superlens.

5. The system of claim 1, further comprising a micro-electro-mechanical system; the micro-electro-mechanical system is configured to adjust a displacement of the light emitting array and/or the first superlens array (10) in a direction perpendicular to the optical axis.

6. The system of claim 5, wherein the micro-electro-mechanical system has a drive stroke of less than or equal to 10 millimeters.

7. The system of claim 5, wherein the micro-electro-mechanical system has a drive precision greater than or equal to 1 micron and less than or equal to 5 microns.

8. The system of claim 5, wherein the operating frequency of the micro-electro-mechanical system is greater than 1 kHz.

9. The system of claim 4, further comprising a wavefront modifier (50); the wavefront modifier (50) is disposed at an entrance pupil of the converging device array (40);

the wavefront modifier (50) is for modifying the focal position of the array of converging means (40).

10. The system of claim 9, wherein the wavefront modifier (50) comprises an array of spatial light modulators, a digital micro-mirror array, or a tunable super-surface spatial light modulator.

11. The system of claim 1 or 4, wherein the first superlens (101) and the second superlens each comprise a substrate and a nanostructure layer disposed on the substrate;

the nanostructure layer comprises nanostructures arranged in an array.

12. The system of claim 11, wherein the nanostructure layer comprises superstructure units arranged in an array;

the superstructure unit is a close-stackable pattern; the center position and/or vertex position of the close-packable pattern is provided with the nanostructure.

13. The system of claim 11, wherein the superlens further comprises a fill material;

the filling material is filled between the nano structures.

14. The system of claim 13, wherein an absolute value of a difference between the refractive index of the filler material and the refractive index of the nanostructures is greater than or equal to 0.5.

15. The system of claim 12, wherein a period of the superstructure unit is greater than or equal to 0.3 λ _c And is less than or equal to 2 lambda _c ；

Wherein λ is _c Is the center wavelength of the operating band of the system.

16. The system of claim 11, wherein the height of the nanostructures is greater than or equal to 0.3 λ _c And is less than or equal to 5 lambda _c ；

Wherein λ is _c Is the center wavelength of the operating band of the system.

17. The system of claim 11, wherein the shape of the nanostructure comprises a polarization sensitive structure.

18. The system of claim 11, wherein the shape of the nanostructure comprises a polarization insensitive structure.

19. The system of claim 11, wherein the superlens further comprises an antireflection film;

20. The system of claim 11, wherein the phase of the first superlens (101) satisfies at least one of the following equations:

wherein r is the distance from the center of the first superlens (101) to the center of any of the nanostructures; lambda is the wavelength of operation and,

21. A lidar scanning method adapted for use with a lidar transmission system of any of claims 1-20, the method comprising:

arranging the light emitting array (20), the first super lens array (10) and the diaphragm array (30) in sequence along a laser emergent direction; the first light beam generated by the light emitting array (20) is converted into a second light beam by the first superlens array (10) and is emitted from the diaphragm array (30); the first light beam is divergent laser with a principal ray parallel to the optical axis of the first super lens array (10); the second light beam is parallel light;

and adjusting the relative positions of the light emitting array (20) and the first super lens array (10) in the direction perpendicular to the optical axis so as to rotate the emergent angle of the second light beam.

22. The method of claim 21, wherein the relative positions satisfy:

Δx＝Ltan(θ _x )；

Δz＝Ltan(θ _z )；

wherein x is a first direction perpendicular to the optical axis, z is a second direction perpendicular to the optical axis, and the x direction is perpendicular to the z direction; l is the distance between the diaphragm array (30) and the first super lens array (10); theta is the rotation angle of the second light beam emitted through the diaphragm array (30).

23. The method according to claim 21 or 22, wherein the light emitting array (20), the first superlens array (10) and the diaphragm array (30) are each a two-dimensional array;

adjusting the relative positions of the light emitting array (20) and the first superlens array (10) in a direction perpendicular to the optical axis so that the second light beam is rotated in a two-dimensional scan.

24. The method according to claim 21 or 22, wherein the light emitting array (20), the first superlens array (10) and the diaphragm array (30) are each one-dimensional arrays;

adjusting the relative positions of the light emitting array (20) and the first superlens array (10) in a direction perpendicular to the optical axis so that the second light beam is rotated in a one-dimensional scan.

25. A wafer-level packaged device adapted for use in a lidar transmission system of any of claims 1-20, the wafer-level packaged device comprising:

an array of light sources arranged in a focal plane of the array of converging means (40); and

a first spacing layer disposed between said array of converging means (40) and said array of light sources, said first spacing layer having a height equal to a focal length of said array of converging means (40);

the first super lens array (10) is arranged on one side of the converging device array (40) far away from the light source array; and the object focal plane of the first superlens array (10) coincides with the focal plane of the converging device array (40);

a second spacing side arranged on a side of the first superlens array (10) remote from the converging device array (40) for supporting a diaphragm array (30);

and the light emitting array (20) and/or the first superlens array (10) are arranged on a displacement platform to enable relative displacement of the light emitting array (20) and the first superlens array (10).