WO2023093118A1 - Telecentric lens and laser radar transmitting and receiving system comprising same - Google Patents

Abstract

A telecentric lens and a laser radar transmitting and receiving system comprising same. The telecentric lens comprises a first super lens (100) and a diaphragm (200), wherein the light energy utilization rate of the first super lens (100) is greater than 75%. The telecentric lens has the advantages of a simple structure, a small size, a high imaging resolution, a low mass production cost, and a high consistency.

Description

Telecentric lens and laser radar transmitting and receiving system including it

Cross reference to related applications

This application claims priority to a Chinese patent application entitled "Telecentric Lens" filed on November 24, 2021 with application number 202111398668.2, the disclosure of which is hereby incorporated by reference.

technical field

The present application relates to the field of optical technology, in particular to a telecentric lens and a laser radar transmitting and receiving system including the same.

Background technique

A telecentric lens is a lens in which the chief ray (that is, the ray passing through the center of the aperture stop) is parallel in object space and/or image space. The telecentric lens has the advantages of constant magnification performance and constant imaging perspective, which can overcome the optical distortion of imaging.

Contents of the invention

A telecentric lens in the related art requires many lenses, and usually high dispersion glass is used to make one or more refractive lenses. Therefore, the traditional telecentric lens has the problems of large size, complicated structure, complicated manufacturing process and high manufacturing cost.

In view of this, in order to solve the technical problems of large size, complex structure, complex manufacturing process and high manufacturing cost of the telecentric lens in the related art, an embodiment of the present application provides a telecentric lens, and the technical solution is as follows.

In the first aspect, the embodiment of the present application provides a telecentric lens, including a first metalens and an aperture; wherein,

The first metalens includes a first planar substrate and a first nanostructure; wherein the first nanostructure is disposed on one side of the first planar substrate, and the first nanostructures are arranged periodically;

Cooperating the diaphragm and the first hyperlens with the optical axis, so that the chief ray angle of the incident light in the object space or image space of the first hyperlens is less than 8°;

And the aspect ratio of the first nanostructure is less than or equal to 20, so that the utilization rate of light energy of the first metalens is greater than or equal to 75%.

In some embodiments of the present application, the phase distribution of the first metalens is rotationally symmetric along the radial direction of the first metalens.

In some embodiments of the present application, the phase of the first metalens at least satisfies any of the following formulas:

Wherein, r is the distance from the center of the first hyperlens to any first nanostructure; (x, y) is the coordinate on the first hyperlens;

is any constant phase; a _i is a coefficient, and a _i satisfies: in the expansion of the above formula, the coefficient of the first r ² term or the first (x ² +y ² ) term is less than 0.

In some embodiments of the present application, the phase of the first metalens at least satisfies any of the following formulas:

Wherein, r is the distance from the center of the first hyperlens to any first nanostructure; (x, y) is the coordinate on the first hyperlens;

is any constant phase; a _i is a coefficient, and a _i satisfies: in the expansion of the above formula, the coefficient of the first r ² term or the first (x ² +y ² ) term is less than 0.

In some embodiments of the present application, the distance between the aperture and the first metalens is less than or equal to one focal length of the first metalens.

In some embodiments of the present application, the aperture is located at the object focal plane of the first hyperlens, so that the incident light passes through the aperture and the first hyperlens in sequence, and in the first hyperlens The chief ray angle of the image space is less than 8°.

In some embodiments of the present application, the aperture is located at the image-space focal plane of the first hyperlens, so that the incident light passes through the first hyperlens and the aperture in sequence, and then exits in parallel.

In some embodiments of the present application, the first metalens further includes a filling material; the filling material is filled between the first nanostructures.

In some embodiments of the present application, the periodic arrangement includes a plurality of first superstructure units arranged in an array;

The shape of the first superstructure unit includes close-packed graphics; the first superstructure unit is arranged on the surface of the first planar substrate;

The first nanostructure is located at the apex and/or the center of the first superstructure unit.

In some embodiments of the present application, the height of the first nanostructure is greater than or equal to 300 nm and less than or equal to 3 μm.

In some embodiments of the present application, the arrangement period of the first nanostructure is greater than 300nm and less than 1500nm.

In some embodiments of the present application, the maximum full field of view angle of the telecentric lens is greater than or equal to 10° and less than or equal to 120°.

In some embodiments of the present application, the aperture of the first metalens is greater than or equal to 2mm and less than or equal to 50mm.

In some embodiments of the present application, the focal length of the first metalens is greater than or equal to 1 mm and less than or equal to 150 mm.

In some embodiments of the present application, the thickness of the first planar substrate is greater than or equal to 50 μm and less than or equal to 5 mm.

In the second aspect, the embodiment of the present application also provides a laser radar emission system, the laser radar emission system includes a light source and a telecentric lens as provided in any of the above embodiments;

The light source is located on the object focal plane of the first metalens of the telecentric lens.

In some embodiments of the present application, the distance error between the light source and the focal plane is less than or equal to FD±2λF ² ;

Wherein, FD is the focal depth of the system of the first hyperlens; F is the F number of the first hyperlens.

In some embodiments of the present application, the radius R of the circumscribed circle of the light source at least satisfies:

R≤f ₁ tanθ

Wherein, θ is the half angle of view of the first hyperlens; f ₁ is the focal length of the first hyperlens.

In the third aspect, the embodiment of the present application also provides a lidar receiving system, including a detector and a telecentric lens as provided in any of the above embodiments;

Wherein, the detector is located on the image-space focal plane of the first metalens of the telecentric lens.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiment of the present application or the background art, the following will describe the drawings that need to be used in the embodiment of the present application or the background art.

FIG. 1A shows an optional structural schematic diagram of a telecentric lens provided by an embodiment of the present application;

Fig. 1B shows another optional structural schematic diagram of the telecentric lens provided by the embodiment of the present application;

Fig. 1C shows another optional structural schematic diagram of the telecentric lens provided by the embodiment of the present application;

Fig. 1D shows another optional structural schematic diagram of the telecentric lens provided by the embodiment of the present application;

FIG. 2 shows an optional structural schematic diagram of a double-sided telecentric lens provided by an embodiment of the present application;

Fig. 3 shows an optional structural schematic diagram of the first superstructure unit provided by the embodiment of the present application;

Fig. 4 shows another optional structural schematic diagram of the first superstructure unit provided by the embodiment of the present application;

FIG. 5A shows a point spread function image of a field of view of a telecentric lens 0 provided by an embodiment of the present application;

FIG. 5B shows a point spread function image of a telecentric lens with a field of view of 0.5 provided by an embodiment of the present application;

FIG. 5C shows a point spread function image of a field of view of a telecentric lens 1 provided by an embodiment of the present application;

FIG. 5D shows a modulation transfer function image of a telecentric lens provided by an embodiment of the present application;

Fig. 6A shows the point spread function image of another telecentric lens 0 field of view provided by the embodiment of the present application;

Fig. 6B shows a point spread function image of another telecentric lens with a field of view of 0.5 provided by the embodiment of the present application;

Fig. 6C shows the point spread function image of another telecentric lens 1 field of view provided by the embodiment of the present application;

Fig. 6D shows a modulation transfer function image of another telecentric lens provided by the embodiment of the present application;

Fig. 7A shows the point spread function image of another telecentric lens 0 field of view provided by the embodiment of the present application;

Fig. 7B shows a point spread function image of another telecentric lens with a field of view of 0.5 provided by the embodiment of the present application;

Fig. 7C shows the point spread function image of another telecentric lens 1 field of view provided by the embodiment of the present application;

Fig. 7D shows a modulation transfer function image of yet another telecentric lens provided by the embodiment of the present application;

Fig. 8A shows the point spread function image of still another telecentric lens 0 field of view provided by the embodiment of the present application;

Fig. 8B shows a point spread function image of yet another telecentric lens with a field of view of 0.5 provided by the embodiment of the present application;

FIG. 8C shows a point spread function image of yet another field of view of the telecentric lens 1 provided by the embodiment of the present application;

FIG. 8D shows another modulation transfer function image of a telecentric lens provided by an embodiment of the present application;

Fig. 9A shows the point spread function image of another telecentric lens 0 field of view provided by the embodiment of the present application;

Fig. 9B shows a point spread function image of another telecentric lens with a field of view of 0.5 provided by the embodiment of the present application;

FIG. 9C shows a point spread function image of another telecentric lens 1 field of view provided by the embodiment of the present application;

FIG. 9D shows another modulation transfer function image of a telecentric lens provided by an embodiment of the present application;

Fig. 10A shows the point spread function image of another telecentric lens 0 field of view provided by the embodiment of the present application;

Figure 10B shows a point spread function image of another telecentric lens with a 0.5 field of view provided by the embodiment of the present application;

Fig. 10C shows a point spread function image of another telecentric lens 1 field of view provided by the embodiment of the present application;

FIG. 10D shows another modulation transfer function image of a telecentric lens provided by an embodiment of the present application;

Fig. 11A shows the point spread function image of another telecentric lens 0 field of view provided by the embodiment of the present application;

Figure 11B shows the point spread function image of another telecentric lens with a field of view of 0.5 provided by the embodiment of the present application;

Fig. 11C shows a point spread function image of another telecentric lens 1 field of view provided by the embodiment of the present application;

Fig. 11D shows the modulation transfer function image of another telecentric lens provided by the embodiment of the present application;

Fig. 12A shows the point spread function image of another telecentric lens 0 field of view provided by the embodiment of the present application;

Fig. 12B shows the point spread function image of another telecentric lens with a field of view of 0.5 provided by the embodiment of the present application;

Fig. 12C shows the point spread function image of another telecentric lens 1 field of view provided by the embodiment of the present application;

Fig. 12D shows the modulation transfer function image of another telecentric lens provided by the embodiment of the present application;

Fig. 13 shows an optional schematic diagram of the lidar transmitting system provided by the embodiment of the present application;

Fig. 14 shows an optional schematic diagram of the lidar receiving system provided by the embodiment of the present application;

Fig. 15A shows the point spread function image of another telecentric lens 0 field of view provided by the embodiment of the present application;

Fig. 15B shows the point spread function image of another telecentric lens with a field of view of 0.5 provided by the embodiment of the present application;

Fig. 15C shows the point spread function image of another telecentric lens 1 field of view provided by the embodiment of the present application;

Fig. 15D shows a modulation transfer function image of yet another telecentric lens provided by the embodiment of the present application;

Fig. 16 shows an optional structural schematic diagram of the second superstructure unit provided by the embodiment of the present application;

FIG. 17 shows another optional structural schematic diagram of the second superstructure unit provided by the embodiment of the present application.

The reference signs in the figure indicate respectively:

100-first hyperlens; 200-aperture; 300-second hyperlens; 400-detector; 500-light source;

101-the first planar substrate; 102-the first nanostructure; 103-the first superstructure unit; 301-the second planar substrate; 302-the second nanostructure; 303-the second superstructure unit;

d ₁ -the diameter of the first hyperlens; d ₂ -the diameter of the entrance pupil; d ₃ -the diameter of the second hyperlens; D-the stop distance; FL-the focal length; P ₁ -the focal plane of the image side; P ₂ -the focal plane of the object ; H-material height.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the implementation manners of the present application will be further described in detail below in conjunction with the accompanying drawings. It should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be A mechanical connection can also be an electrical connection: it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the embodiments of the present application in specific situations.

It should be understood that in the description of the present application, terms such as "first" and "second" are only used for distinction, and do not represent order, priority or quantity. If there is no conflict, the features in the following embodiments and implementations can be combined with each other.

The embodiment of the present application provides a telecentric lens, as shown in FIG. 1A to FIG. 2 , the telecentric lens includes a first hyperlens 100 and an aperture 200 .

Wherein, the first metalens 100 includes a first planar substrate 101 and a first nanostructure 102 . Wherein, the first nanostructures 102 are disposed on one side of the first planar substrate 101, and the first nanostructures 102 are arranged periodically. The diaphragm 200 and the first hyperlens 100 are matched with the optical axis so that the chief ray angle of the incident light in the object space or image space of the first hyperlens 100 is less than 8°; and the aspect ratio of the first nanostructure 102 is less than or is equal to 20, so that the light energy utilization rate of the first metalens 100 is greater than or equal to 75%.

Specifically, the diaphragm 200 controls the amount of incident light, and cooperates with the modulation of the light phase by the first nanostructure 102 on the surface of the first hyperlens 100 to improve the parallelism of the chief ray, so that the telecentric lens can eliminate aberrations and Distortion, improve imaging accuracy. The aspect ratio of the first nanostructure 102 satisfies: Aspect ratio=h/CD; wherein, CD is the characteristic dimension of the first nanostructure 102, and h is the height of the first nanostructure. If the aspect ratio exceeds 20, it will cause resonance of nanostructures or photons, which will affect the transmittance.

The telecentricity describes the angle at which the chief ray deviates from the optical axis (ie, the chief ray angle). The smaller the angle, the better the telecentricity and the more accurate the imaging. Further, the phase distribution of the first metalens 100 provided in the embodiment of the present application is preferably rotationally symmetrical along the radial direction of the first metalens 100, so as to improve the telecentricity of the telecentric lens.

More advantageously, in order to further improve the telecentricity of the telecentric lens, the phase of the first metalens 100 at least satisfies any of the following formulas:

Wherein, r is the distance from the center of the hyperlens 100 to any first nanostructure 102; (x, y) is the coordinate on the first hyperlens 100;

is any constant phase; a _i is a coefficient, and a _i satisfies: in the expansion of the above formulas (1) and (2), the coefficient of the first r ² term or the first (x ² +y ² ) term is less than 0. The phase of the first metalens 100 can be expressed as an even degree polynomial, and formulas (1) and (2) only optimize the phase satisfying the even degree polynomial.

More advantageously, in order to further improve the telecentricity of the telecentric lens, the phase of the first metalens 100 at least satisfies any of the following formulas:

Wherein, r is the distance from the center of the first hyperlens 100 to any first nanostructure 102; (x, y) is the coordinate on the first hyperlens 100;

is any constant phase; a _i is a coefficient, and a _i satisfies: in the expansion of the above formulas (3) and (4), the coefficient of the first r ² term or the first (x ² +y ² ) term is less than 0. Compared with formula (1) and formula (2), formula (3) and formula (4) can not only optimize the phase that satisfies the even degree polynomial, but also can optimize the phase that satisfies the odd degree polynomial, so that the first super The degree of freedom of design of the lens 100 is higher.

Optionally, the distance between the diaphragm 200 and the first metalens 100 , that is, the distance of the diaphragm is less than or equal to one focal length of the first metalens 100 is beneficial to improve the imaging effect of the telecentric lens. Preferably, the focal length of the first metalens 100 is greater than or equal to 1 mm and less than or equal to 150 mm. The aperture distance is used to control the incident light of different angles on different positions of the first metalens, so as to realize aberration correction. If the aperture distance is greater than one focal length of the first hyperlens, then the first hyperlens needs to have a larger aperture, which is not conducive to the miniaturization of the telecentric lens, and will cause the total system length (TTL, Total Tracking Length) increased. The total system length of the telecentric lens is the distance from the object-side surface of the diaphragm to the image plane (P ₁ ) of the first metalens.

In order to reduce the volume of the telecentric lens without affecting the imaging effect, in some optional embodiments of the present application, the diameter d ₁ of the first hyperlens 100 is greater than or equal to 2 mm and less than or equal to 50 mm. More advantageously, the thickness of the first planar substrate 101 of the first metalens 100 is greater than or equal to 50 μm and less than or equal to 5 mm.

The first planar substrate 101 of the first metalens 100 provided in the embodiment of the present application has high transparency to radiation in the working band. Optionally, the extinction coefficient of the first planar substrate 101 for the working wavelength band is less than 0.1. Preferably, the extinction coefficient of the first planar substrate 101 for the working wavelength band is less than 0.01. The material of the first planar substrate 101 includes materials such as fused silica, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon. The material of the first nanostructure 102 and the material of the first planar substrate 101 may be the same or different. Preferably, the material of the first nanostructure 102 is different from that of the first planar substrate 101 . Exemplarily, the material of the first nanostructure 102 includes silicon oxide, silicon nitride, aluminum oxide, gallium nitride, titanium oxide and amorphous silicon. Based on the above materials, the peak laser power that the first metalens 100 can withstand is greater than or equal to 0.3W.

It should be understood that the working wavebands of the telecentric lens include visible light wavebands, near-infrared wavebands, mid-infrared wavebands, far-infrared wavebands, ultraviolet light wavebands, deep ultraviolet light wavebands and extreme deep ultraviolet light wavebands. Preferably, the working wavelength band of the telecentric lens includes 905nm±15nm, 940nm±15nm or 1550nm±20nm.

The position of the first nanostructure 102 on the first planar substrate 101 is selected according to actual needs. The first nanostructure 102 can be located on the same side of the diaphragm 200, or on a side away from the diaphragm 200. For example, FIG. 1A shows that the first nanostructure 102 is disposed on the surface of the first planar substrate 101 facing the diaphragm 200 . As another example, FIG. 1B shows that the first nanostructure 102 is disposed on the surface of the first planar substrate 101 away from the diaphragm 200 .

In Fig. 1A and Fig. 1B, d ₁ is the caliber of the first hyperlens 100, d ₂ is the entrance pupil diameter of the telecentric lens, D is the aperture distance of the telecentric lens provided by the embodiment of the present application, and FL is the distance The focal length of the telecentric lens, θ is the half angle of view of the telecentric lens, and P ₁ is the image plane (image square focal plane) of the telecentric lens. Exemplarily, the F number of the telecentric lens is greater than or equal to 1 and less than or equal to 10. The F-number is the focal length FL of the first hyperlens 100 and the entrance pupil diameter d ₂ of the first hyperlens 100 .

Further, as shown in FIG. 3 and FIG. 4 , the periodic arrangement of the first nanostructures 102 includes a plurality of first superstructure units 103 arranged in an array. The shape of the first superstructure unit 103 includes close-packed patterns, and the first superstructure unit 103 is disposed on the surface of the first planar substrate 101 . The first nanostructure 102 is disposed at the apex and/or the center of the first superstructure unit 103 . Fig. 3 and Fig. 4 only show the embodiment that the first superstructure unit 103 includes regular hexagons and regular quadrilaterals. The first superstructure unit 103 also includes fan shapes and other close-packable figures. The shapes of the first superstructure units 103 may be all the same, partly the same, or different from each other. For the same metalens, the shape of the superstructure unit will affect the arrangement density of nanostructures on the metalens, or the number of nanostructures that can be placed on a substrate per unit area. Preferably, the regular hexagonal superstructure unit used in the first metalens 100 saves 13% of nanostructures compared with the regular quadrilateral superstructure unit, which is beneficial to reduce the production cost and process difficulty of the first metalens. And, when the first nanostructures are regularly arranged in a regular hexagon, the distance between any first nanostructure and its surrounding six adjacent nanostructures is equal; and when the first nanostructures are arranged in a regular quadrilateral, any There are two different distances between the first nanostructure and its surrounding eight adjacent nanostructures, that is, the distance between the nanostructures is not uniform, which leads to poor periodicity of the arrangement of the first nanostructure, and the poor periodicity will lead to super When the lens is obliquely incident at a large angle (incident angle greater than 20°), the transmittance is seriously reduced.

Periods of the first superstructure units 103 may be all the same, or may be partly the same, or may be different from each other. Preferably, the arrangement period of the first nanostructure 102, that is, the period of the first superstructure unit 103 is greater than 300 nm and less than 1500 nm. The shape and period of the first superstructure unit 103 can be modulated according to the phase of the first superlens 100 . For the working wavelength band (wavelength 450nm to 1550nm) of the telecentric lens provided in the embodiment of the present application, such as the near-infrared band and visible light band, the first nanostructure is a corresponding sub-wavelength structure. Therefore, optionally, for the near-infrared band, the arrangement period of the first nanostructures is less than or equal to 1500 nm; optionally, for the blue-visible band, the arrangement period of the first nanostructures is less than or equal to 450 nm. It should be noted that if the arrangement period of the first nanostructures is too small, for example, less than or equal to one-half of the wavelength, it will cause the coupling between adjacent first nanostructures to generate resonance, thus resulting in the transmission of the first metalens. Overrate drops.

Furthermore, the geometric dimensions of the first nanostructure 102, including the height of the nanostructure, the cross-sectional diameter of the nanostructure, and the spacing between the nanostructures, can be selected according to the requirements of different situations. The first nanostructure 102 is a sub-wavelength structure, that is to say, the characteristic size of the first nanostructure 102 is smaller than or equal to the working wavelength of the telecentric lens. Optionally, the feature size of the first nanostructure 102 is slightly larger than the working wavelength. Preferably, the height of the first nanostructure 102 is greater than or equal to 300 nm and less than or equal to 3 μm. In some embodiments of the present application, the minimum size of the first nanostructure 102 (diameter, side length and/or the minimum distance between two adjacent nanocolumn structures, etc.) is greater than or equal to 60 nm.

Exemplarily, the maximum aspect ratio of the first nanostructure 102, that is, the ratio of the height of the first nanostructure 102 to the minimum diameter of the first nanostructure 102 in the first metalens 100, is less than or equal to 20, so as to guarantee the The optical properties of the first nanostructure 102 are ensured while the mechanical properties of the first nanostructure 102 are ensured. The cross-sectional diameters of the first nanostructures 102 at different positions are partly the same or different from each other; the structural periods of the first nanostructures 102 at different positions are the same; diameter dependent. It can be understood that the geometric shape and size of the first nanostructure 102 can be other options that meet detection requirements and processing conditions. Exemplarily, the structure of the first nanostructure 102 includes at least one or a combination of structures such as nanocolumns, nanosquare columns, nanofins, nanoring columns, and hollow nanocolumns. In an optional implementation manner, the first metalens 100 further includes a filling material filled between the nanostructures 102 . Depending on the phase of the first metalens 100, the shape, size and filling material of the nanostructures 102 can be selected.

Optionally, the maximum full field angle of the telecentric lens is greater than or equal to 10° and less than or equal to 120°. The imaging accuracy of the telecentric lens can be ensured if the maximum full field of view is in the range of 10° to 120°.

Generally speaking, the uniform illuminance of the image plane of the telecentric lens is determined by the telecentricity of the image side. If the telecentric lens is an object-space telecentric lens, the light emitted through the aperture has high parallelism, and can be used in laser emission systems and machine vision. If the telecentric lens is an image-side telecentric lens, the chief ray of the telecentric lens is perpendicular to the image plane, and the illuminance on the image plane is uniform. Bi-telecentric lenses have the advantages of both object-space telecentricity and image-space telecentricity, and can be used in microscopic objectives and machine vision.

In an optional implementation manner, as shown in FIGS. 1A and 1B , the telecentric lens provided in the embodiment of the present application includes a first hyperlens 100 and an aperture 200 . Wherein, the diaphragm 200 is located on the object focal plane of the first hyperlens 100, so that the incident light passes through the diaphragm 200 and the hyperlens 100 in sequence, and the chief ray angle in the image space of the first hyperlens 100 is less than 8°. The first metalens 100 includes a first planar substrate 101 and a first nanostructure 102 . Wherein, the first nanostructures 102 are disposed on one side of the first planar substrate 101, and the first nanostructures 102 are arranged periodically. That is, the telecentric lens is an image-side telecentric lens, and the illuminance of the telecentric lens on the image plane _P1 is uniform.

In yet another optional implementation manner, as shown in FIG. 1C and FIG. 1D , the telecentric lens provided in the embodiment of the present application includes a first hyperlens 100 and an aperture 200 . Wherein, the diaphragm 200 is located at the focal plane of the image space of the first hyperlens 100, so that the incident light passes through the hyperlens 100 and the diaphragm 200 in sequence, and the principal ray angle in the object space of the first hyperlens 100 is less than 8°. The first metalens 100 includes a first planar substrate 101 and a first nanostructure 102 . Wherein, the first nanostructures 102 are disposed on one side of the first planar substrate 101, and the first nanostructures 102 are arranged periodically. That is, the telecentric lens is an object-space telecentric lens, which can be used in a laser radar transmitting system.

It should be understood that the principal rays are parallel in the object space, the image space, or the object space and the image space, which is determined by the usage scenario of the telecentric lens provided in the embodiment of the present application. Determine the position of the first nanostructure 102 on the first planar substrate 101, the number of surfaces of the first planar substrate 101 with the first nanostructure 102, and the position of the diaphragm 200 on the first metalens 100 according to the usage scenario of the telecentric lens, The space in which the chief ray of the telecentric lens is parallel can be adjusted. The first superlens 100 adopts a first planar substrate 101, and the first nanostructure 102 is a sub-wavelength structure, so that the first superlens 100 can be mass-produced through a photolithography process, thereby reducing the mass production cost of the first superlens 100, and Improve mass production consistency.

It should be noted that the design parameters of the telecentric lens can be adjusted according to different conditions such as application scenarios and working bands to obtain a telecentric lens that meets actual needs. The following examples provide the parameters of the telecentric lens provided in the examples of the present application when the chief ray angle is less than 8° in the wavelength bands of 905 nm, 940 nm, and 1550 nm.

Example 1

The embodiment of the present application provides a telecentric lens as shown in FIG. 1B , the specific parameters are shown in Table 1A, and the implementation effect of the telecentric lens is shown in Table 1B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in FIGS. 5A to 5C , and the corresponding modulation transfer functions are shown in FIG. 5D .

Table 1A

parameter (unit)	value
wavelength(nm)	940
Diameter (mm)	3.8
Half field angle (°)	25
Aperture distance (mm)	2
focal length(mm)	3

Table 1B

As shown in Table 1B, the chief ray angle of the telecentric lens provided in Example 1 is less than or equal to 0.6°. 5A to 5C show the point spread function of light modulated by the telecentric lens. As shown in FIGS. 5A to 5C , the point spread function of the telecentric lens provided by Embodiment 1 has low ambiguity and clear imaging. FIG. 5D shows that the modulation transfer functions of the telecentric lens provided in Embodiment 1 all reach the diffraction limit under different fields of view, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 2

The embodiment of the present application provides a telecentric lens as shown in FIG. 1B , the specific parameters are shown in Table 2A, and the implementation effect of the telecentric lens is shown in Table 2B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in FIGS. 6A to 6C , and the corresponding modulation transfer functions are shown in FIG. 6D .

Table 2A

parameter (unit)	value
wavelength(nm)	940
Diameter (mm)	8.4
Half field angle (°)	25
Aperture distance(mm)	6.5
focal length(mm)	6.55

Table 2B

As shown in Table 2B, the chief ray angle of the telecentric lens provided in Example 2 is less than or equal to 1°. 6A to 6C show the point spread function of light modulated by the telecentric lens. As shown in FIGS. 6A to 6C , the point spread function of the telecentric lens provided by Embodiment 2 has low ambiguity and clear imaging. FIG. 6D shows that the modulation transfer functions of the telecentric lens provided by Embodiment 2 all reach the diffraction limit under different fields of view, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 3

The embodiment of the present application provides a telecentric lens as shown in FIG. 1A , the specific parameters are shown in Table 3A, and the implementation effect of the telecentric lens is shown in Table 3B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in FIGS. 7A to 7C , and the corresponding modulation transfer functions are shown in FIG. 7D .

Table 3A

parameter (unit)	value
wavelength(nm)	940
Diameter (mm)	2
Half field angle (°)	10
Aperture distance (mm)	1.8
focal length(mm)	2.16

Table 3B

As shown in Table 3B, the chief ray angle of the telecentric lens provided in Example 3 is less than or equal to 3°. 7A to 7C show the point spread function of light modulated by the telecentric lens. As shown in FIGS. 7A to 7C , the point spread function of the telecentric lens provided by Embodiment 3 has low ambiguity and clear imaging. FIG. 7D shows that the modulation transfer functions of the telecentric lens provided by Example 3 under different fields of view do not exceed the diffraction limit, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 4

The embodiment of the present application provides a telecentric lens as shown in FIG. 1B , the specific parameters are shown in Table 4A, and the implementation effect of the telecentric lens is shown in Table 4B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in FIGS. 8A to 8C , and the corresponding modulation transfer functions are shown in FIG. 8D .

Table 4A

parameter (unit)	value
wavelength(nm)	1550
Diameter (mm)	16.2
Half field angle (°)	30
Aperture distance (mm)	9.5
focal length(mm)	10

Table 4B

As shown in Table 4B, the chief ray angle of the telecentric lens provided in Example 4 is less than or equal to 7.6°. 8A to 8C show the point spread function of light modulated by the telecentric lens. As shown in FIGS. 8A to 8C , the point spread function of the telecentric lens provided by Embodiment 4 has low ambiguity and clear imaging. FIG. 8D shows that the modulation transfer functions of the telecentric lens provided by Embodiment 4 under different fields of view do not exceed the diffraction limit, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 5

The embodiment of the present application provides a telecentric lens as shown in FIG. 1A , the specific parameters are shown in Table 5A, and the implementation effect of the telecentric lens is shown in Table 5B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in Figures 9A to 9C, and the corresponding modulation transfer functions are shown in Figure 9D.

Table 5A

parameter (unit)	value
wavelength(nm)	1550
Diameter (mm)	20
Half field angle (°)	45
Aperture distance (mm)	8
focal length(mm)	10

Table 5B

As shown in Table 5A, the chief ray angle of the telecentric lens provided by Example 5 is less than or equal to 5.1°. 9A to 9C show the point spread function of light modulated by the telecentric lens. As shown in FIGS. 9A to 9C , the point spread function of the telecentric lens provided by Embodiment 5 has low ambiguity and clear imaging. FIG. 9D shows that the modulation transfer functions of the telecentric lens provided by Embodiment 5 under different fields of view do not exceed the diffraction limit, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 6

The embodiment of the present application provides a telecentric lens as shown in FIG. 1A , the specific parameters are shown in Table 6, and the implementation effect of the telecentric lens is shown in Table 6B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in FIGS. 10A to 10C , and the corresponding modulation transfer functions are shown in FIG. 10D .

Table 6A

parameter (unit)	value
wavelength(nm)	1550
Diameter (mm)	32
Half field angle (°)	60
Aperture distance (mm)	8.8
focal length(mm)	10

Table 6B

As shown in Table 6B, the chief ray angle of the telecentric lens provided in Example 6 is less than or equal to 7.92°. Figures 10A to 10C show the point spread function of the light modulated by the telecentric lens. As shown in Figures 10A to 10C, the point spread function of the telecentric lens provided in Embodiment 6 has low ambiguity and clear imaging. FIG. 10D shows that the modulation transfer functions of the telecentric lens provided by Embodiment 6 under different fields of view do not exceed the diffraction limit, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 7

The embodiment of the present application provides a telecentric lens as shown in FIG. 1B , the specific parameters are shown in Table 7A, and the implementation effect of the telecentric lens is shown in Table 7B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in FIGS. 11A to 11C , and the corresponding modulation transfer functions are shown in FIG. 11D .

Table 7A

parameter (unit)	value
wavelength(nm)	1550
Diameter (mm)	5.8
Half field angle (°)	13.6
Aperture distance(mm)	6.5
focal length(mm)	7

Table 7B

As shown in Table 7B, the chief ray angle of the telecentric lens provided by Example 7 is less than or equal to 0.2°. 11A to 11C show the point spread function of light modulated by the telecentric lens. As shown in FIGS. 11A to 11C , the point spread function of the telecentric lens provided by Embodiment 7 has low ambiguity and clear imaging. FIG. 11D shows that the modulation transfer functions of the telecentric lens provided by Example 7 under different fields of view do not exceed the diffraction limit, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 8

The embodiment of the present application provides a telecentric lens as shown in FIG. 1B , the specific parameters are shown in Table 8A, and the implementation effect of the telecentric lens is shown in Table 8B. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in FIGS. 12A to 12C , and the corresponding modulation transfer functions are shown in FIG. 12D .

Table 8A

parameter (unit)	value
wavelength(nm)	905
Diameter (mm)	6.4

Half field angle (°)	20
Aperture distance(mm)	5.9
focal length(mm)	6

Table 8B

As shown in Table 8B, the chief ray angle of the telecentric lens provided in Example 8 is less than or equal to 0.1°. 12A to 12C show the point spread function of light modulated by the telecentric lens. As shown in FIGS. 12A to 12C , the point spread function of the telecentric lens provided by Embodiment 8 has low ambiguity and clear imaging. FIG. 12D shows that the modulation transfer functions of the telecentric lens provided by Embodiment 8 under different fields of view do not exceed the diffraction limit, that is, the resolution of the telecentric lens is good and the imaging is clear.

Example 9

The embodiment of the present application provides a telecentric lens as shown in FIG. 1D , the specific parameters are shown in Table 9A, and the implementation effect of the telecentric lens is shown in Table 9B. As shown in Table 9B, the implementation effect of the object-space telecentric lens can also be measured by the degree of parallelism, and the smaller the value of the parallelism, the better the implementation effect of the object-space telecentric lens.

Table 9A

parameter (unit)	value
wavelength(nm)	940
Diameter (mm)	2
Object height(mm)	0.51
Half field angle (°)	10
Aperture distance (mm)	2.5
focal length(mm)	2.16

Table 9B

Example 10

The embodiment of the present application provides a telecentric lens as shown in FIG. 1C , the specific parameters are shown in Table 10A, and the implementation effect of the telecentric lens is shown in Table 10B. As shown in Table 10B, the implementation effect of the object-space telecentric lens can also be measured by parallelism, and the smaller the value of the parallelism, the better the implementation effect of the object-space telecentric lens.

Table 10A

parameter (unit)	value
wavelength(nm)	1550
Diameter (mm)	6
Object height(mm)	3
Half field angle (°)	14
Aperture distance (mm)	6.5
focal length(mm)	7

Form 10B

The embodiment of the present application also provides a laser radar transmitting system, as shown in FIG. 13 , the laser radar transmitting system includes a light source 500 and the telecentric lens 100 provided in any of the above embodiments. Wherein, the light source 500 is located on the focal plane of the first metalens 100 . Preferably, the telecentric lens is an object-space telecentric lens, that is, the diaphragm 200 is located at the image-space focal plane of the first metalens 100 , and the light source 500 is located at the object-space focal plane of the first metalens 100 . Optionally, the telecentric lens is an image-space telecentric lens, and if the image-space telecentric lens is reversely installed in front of the light exit surface of the light source 500 , the outgoing rays passing through the diaphragm 200 can be parallelized.

Preferably, the distance error between the light source 500 and the focal plane of the metalens 100 is less than or equal to FD±2λF ² , where FD is the system focal depth of the metalens 100 ; F is the F-number of the metalens 100 . In this way, it can be ensured that the light source is on the focal plane of the metalens 100, so that defocusing will not occur.

Further, the radius of the circumscribed circle of the light source 500 at least satisfies:

R≤f tanθ (5)

Wherein, R is the radius of the circumscribed circle of the light source 500 ; θ is the half field angle of the first metalens 100 ; f is the focal length of the first metalens 100 .

Furthermore, the light source 500 includes a laser light source and a laser light source array. For example, the light source 500 includes a Vertical-Cavity Surface-Emitting Laser (VCSEL, Vertical-Cavity Surface-Emitting Laser) and an Edge Emitting Laser (EEL, Edge Emitting Laser). Optionally, the working wavelength bands of the light source 500 include visible light bands, near-infrared bands, mid-infrared bands, far-infrared bands, ultraviolet light bands, deep ultraviolet light bands, and extreme deep ultraviolet light bands. In an exemplary embodiment of the present application, the working wavelength of the light source 500 includes 905nm±15nm, 940nm±15nm or 1550nm±20nm. Preferably, the light source 500 realizes far-field scanning by using partition lighting.

The laser radar emission system provided by the embodiment of the present application adopts the combination of the telecentric lens provided by the embodiment of the present application and the laser light source, and uses the telecentric lens to improve the parallelism of the outgoing light of the laser radar emission system and increase the effective detection distance of the laser radar. ; Through the advantages of small volume and simple structure of the telecentric lens provided by the embodiment of the present application, the size of the laser radar transmitting system is reduced, the structure of the laser radar transmitting system is simplified, and the cost of the laser radar transmitting system is reduced.

An embodiment of the present application also provides a laser radar receiving system, as shown in FIG. 14 , the laser radar transmitting system includes a detector 400 and a telecentric lens provided in any of the above embodiments. Wherein, the detector 400 is located on the focal plane of the first metalens 100 . Preferably, the telecentric lens is an image-space telecentric lens, that is, the diaphragm 200 is located at the object-space focal plane of the first metalens 100 , and the detector 400 is located at the image-space focal plane of the first metalens 100 . Optionally, the telecentric lens is an object-space telecentric lens, and the object-space telecentric lens is reversely installed in front of the light-receiving surface of the detector 400, so that the chief ray angle of the light emitted through the first metalens 100 can be smaller than 8°, so that the illumination on the detector 400 is uniform.

Preferably, the distance error between the detector 400 and the focal plane of the first metalens 100 is less than or equal to FD±2λF ² , where FD is the system focal depth of the first metalens 100; F is the F number of the first metalens 100 .

Further, the radius of the circumscribed circle of the detector 400 at least satisfies:

R≤f ₁ tanθ (5)

Wherein, θ is the half field angle of the first hyperlens 100 ; f ₁ is the focal length of the first hyperlens 100 .

Furthermore, the detector 400 includes a charge coupled device (CCD, Charge Coupled Device), a complementary metal oxide semiconductor (CMOS, Complementary Metal Oxide Semiconductor Transistor), a vanadium oxide detector, an amorphous silicon detector, an indium gallium arsenide detector , Lead sulfide detectors, lead selenide detectors. In an exemplary embodiment of the present application, the working wavelength of the detector 400 includes 905nm±15nm, 940nm±15nm or 1550nm±20nm.

The lidar receiving system provided by the embodiment of the present application adopts the combination of the telecentric lens and the detector provided by the embodiment of the present application, and uses the telecentric lens to improve the uniformity of illumination of the detector and improve the imaging definition of the lidar; through this The telecentric lens provided by the embodiment of the application has the advantages of small volume and simple structure, which reduces the size of the laser radar receiving system, simplifies the structure of the laser radar transmitting and receiving system, and reduces the cost of the laser radar receiving system.

The embodiment of the present application also provides a laser radar system, the laser radar system includes the laser radar transmitting system provided by any of the above embodiments, the laser radar receiving system provided by any of the above embodiments, and a control processing unit; the control processing unit and The laser radar transmitting system is connected with the laser radar receiving system.

The laser radar system provided by the embodiment of the present application improves the effective detection distance and imaging definition of the laser radar system through the telecentric lens provided by the embodiment of the present application, reduces the size of the laser radar system, and simplifies the structure of the laser radar system , reducing the cost of the lidar system.

In some optional implementations, as shown in FIG. 2 , the telecentric lens further includes a second hyperlens 300, so that the first hyperlens 100 and the second hyperlens 300 form a 4f optical system, thereby forming a double-sided telecentric lens. heart system. The second hyperlens 300 includes a second planar substrate 301 and second nanostructures 302; the second nanostructures 302 are disposed on one side of the second planar substrate 301, and the second nanostructures 302 are arranged periodically. The second hyperlens 300 is confocal with the first hyperlens 100 ; the diaphragm 200 is located at the confocal position of the second hyperlens 300 and the first hyperlens 100 . Optionally, the aspect ratio of the second nanostructure 302 is less than or equal to 20, so that the utilization rate of light energy of the second metalens 300 is greater than or equal to 75%. The design idea of the second metalens is similar to that of the first metalens.

Specifically, in the telecentric lens shown in Figure 2, the first hyperlens 100 and the second hyperlens 300 are confocally arranged to form a 4f optical system, so that the principal rays in the object space and image space of the telecentric lens The angles are all less than 8°. Optionally, when the telecentric lens is an image-space telecentric lens, the object-space focal point of the first hyperlens 100 coincides with the image-space focal point of the second hyperlens 300, and the stop 200 is positioned at the hyperlens 100 and the confocal point of the second metalens 300. Optionally, as shown in FIG. 2, when the telecentric lens is an object-space telecentric lens in the telecentric lens, the image-space focal point of the first hyperlens 100 coincides with the object-space focal point of the second hyperlens 300, and the light Stop 200 is located at the confocal point of first metalens 100 and second metalens 300 . That is to say, in the telecentric lens, the second hyperlens 300 and the diaphragm 200 of the telecentric lens form a new telecentric lens. Thus, the telecentric lens consists of two metalens sharing the same aperture.

Optionally, the phase distribution of the second metalens 300 provided in the embodiment of the present application is preferably rotationally symmetrical along the radial direction of the second metalens 300, so as to improve the telecentricity of the telecentric lens.

More advantageously, in order to further improve the telecentricity of the telecentric lens, the phase of the second metalens 300 at least satisfies any of the following formulas:

Wherein, r is the distance from the center of the second hyperlens 300 to any second nanostructure 302; (x, y) is the coordinate on the second hyperlens 300;

is any constant phase; a _i is a coefficient, and a _i satisfies: the coefficient of the first r ² item in the above formulas (1) and (2) is less than 0.

More advantageously, in order to further improve the telecentricity of the telecentric lens, the phase of the second metalens 300 at least satisfies any of the following formulas:

Wherein, r is the distance from the center of the second hyperlens 300 to any second nanostructure 302; (x, y) is the coordinate on the second hyperlens 300;

is any constant phase; a _i is a coefficient, and a _i satisfies: the coefficient of the first r ² item in the above formulas (3) and (4) is less than 0. Optionally, the distance between the diaphragm 200 and the second metalens 300 is less than or equal to one focal length of the second metalens 300, which is beneficial to improve the imaging effect of the telecentric lens. Preferably, the focal length of the second hyperlens 300 is greater than or equal to 1 mm and less than or equal to 150 mm. In order to reduce the volume of the telecentric lens without affecting the imaging effect, in some optional embodiments of the present application, the diameter d ₃ of the second hyperlens 300 is greater than or equal to 2 mm and less than or equal to 50 mm. More advantageously, the thickness of the second planar substrate 301 of the metalens 300 is greater than or equal to 50 μm and less than or equal to 5 mm.

The second planar substrate 301 of the second metalens 300 provided in the embodiment of the present application has high transparency to radiation in the working wavelength band. Optionally, the extinction coefficient of the second planar substrate 301 for the working wavelength band is less than 0.1. Preferably, the extinction coefficient of the second planar substrate 301 for the working wavelength band is less than 0.01. The material of the second planar substrate 301 includes materials such as fused silica, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon. The material of the second nanostructure 302 and the material of the second planar substrate 301 may be the same or different. Preferably, the material of the second nanostructure 302 is different from that of the second planar substrate 301 . Exemplarily, the material of the second nanostructure 302 includes silicon oxide, silicon nitride, aluminum oxide, gallium nitride, titanium oxide and amorphous silicon. Based on the above materials, the peak laser power that the second metalens 300 can withstand is greater than or equal to 0.3W.

The position of the second nanostructure 302 on the second planar substrate 301 is selected according to actual requirements. The second nanostructure 302 can be located on the same side of the diaphragm 200 or on a side away from the diaphragm 200 . Preferably, the second nanostructures 302 of the second metalens 300 and the first nanostructures 102 of the first metalens 100 face oppositely.

In FIG. 2 , d ₁ is the diameter of the first metalens 100 , and d ₃ is the diameter of the second metalens 300 . Exemplarily, the F number of the second hyperlens 300 is greater than or equal to 1 and less than or equal to 10. f ₂ is the focal length of the second metalens 300 and f ₁ is the focal length of the first metalens 100 . The F-number is the ratio of the focal length of the second hyperlens 300 to the exit pupil diameter of the second hyperlens 300 . Since the second hyperlens 300 and the first hyperlens 100 share the same diaphragm 200 , the exit pupil diameter of the second hyperlens 300 is equal to the entrance pupil diameter d ₂ of the first hyperlens 100 .

Further, similar to the arrangement of the first nanostructures 102 , as shown in FIGS. 16 and 17 , the periodic arrangement of the second nanostructures 302 includes a plurality of second superstructure units 303 arranged in an array. The shape of the second superstructure unit 303 includes close-packed graphics, and the second superstructure unit 303 is disposed on the surface of the second planar substrate 301 . The second nanostructure 302 is disposed at the apex and/or the center of the second superstructure unit 303 . Exemplarily, as shown in FIG. 16 and FIG. 17 , the shape of the second superstructure unit 303 includes a hexagon or a square. The second superstructure unit 303 also includes fan shapes and other close-packable figures. The shapes of the second superstructure units 303 may be all the same, partly the same, or different from each other. Periods of the second superstructure units 303 may be all the same, partly the same, or different from each other. Preferably, the arrangement period of the second nanostructure 302, that is, the period of the second superstructure unit 303 is greater than 300 nm and less than 1500 nm. The shape and period of the second superstructure unit 303 can be modulated according to the phase of the second superlens 300 .

Furthermore, the geometric dimensions of the second nanostructure 302, including the height of the nanostructure, the cross-sectional diameter of the nanostructure, and the distance between the nanostructures, can be selected according to the requirements of different situations. The second nanostructure 302 is a sub-wavelength structure, that is to say, the characteristic size of the second nanostructure 303 is smaller than or equal to the working wavelength of the telecentric lens. Optionally, the characteristic size of the second nanostructure 302 is slightly larger than the working wavelength. Preferably, the height of the second nanostructure 302 is greater than or equal to 300 nm and less than or equal to 3 μm. In some embodiments of the present application, the minimum size of the second nanostructure 302 (diameter, side length and/or minimum distance between two adjacent nanostructures, etc.) is greater than or equal to 60 nm.

Exemplarily, the maximum aspect ratio of the second nanostructure 302, that is, the ratio of the height of the second nanostructure 302 to the minimum diameter of the second nanostructure 302 in the second metalens 300, is less than or equal to 20, so as to guarantee The optical performance of the second nanostructure 302 ensures the mechanical performance of the second nanostructure 302 at the same time. The cross-sectional diameters of the second nanostructure 302 at different positions are partly the same or different from each other; the structural period of the second nanostructure 302 at different positions is the same; diameter dependent. It can be understood that the geometric shape and size of the second nanostructure 302 can be other options that meet detection requirements and processing conditions. Exemplarily, the structure of the second nanostructure 302 includes at least one or a combination of structures such as nanocolumns, nanosquare columns, nanofins, nanoring columns, and hollow nanocolumns. In an optional embodiment, the second metalens 300 includes a filling material filled between the second nanostructures 302 . It should be understood that the filling material is transparent in the working wavelength band of the telecentric lens. Depending on the phase of the second metalens 300, the shape, size and filling material of the second nanostructure 302 can be selected.

Optionally, the maximum full field angle of the telecentric lens is greater than or equal to 10° and less than or equal to 120°. The imaging accuracy of the telecentric lens can be ensured if the maximum full field of view is in the range of 10° to 120°.

Example 11

The embodiment of the present application provides a telecentric lens as shown in FIG. 2 , and specific parameters are shown in Table 11. The point spread functions of the three fields of view (0 field of view, 0.5 field of view and 1.0 field of view) of the telecentric lens are shown in Figures 15A to 15C, and the corresponding modulation transfer functions are shown in Figure 15D.

Table 11

parameter (unit)	value
wavelength(nm)	940
Second hyperlens diameter d 3 (mm)	6
Object height(mm)	1.5
First hyperlens aperture d 1 (mm)	5
Image height(mm)	1.25
Second hyperlens focal length f 2 (mm)	6
First hyperlens focal length f 1 (mm)	5

In the telecentric lens provided in the embodiment of the present application, the first metalens and the second metalens form a 4f optical system, thereby forming a double-sided telecentric system. The incident light passes through the second hyperlens and exits parallel to the diaphragm, and the parallel exiting light passes through the first hyperlens, and the chief ray angle is less than 8°, so that the illumination of the image plane is uniform. The imaging illuminance of the telecentric lens is uniform, and the image height does not change with the change of the object distance. Therefore, the telecentric lens can be used in fields such as microscopic objective lens, machine vision and photolithography processing.

The embodiment of the present application also provides an optical device, including the telecentric lens described in the above embodiment. Optionally, the optical device is a microscope objective.

To sum up, the telecentric lens provided by the embodiment of the present application realizes that the chief ray angle of the chief ray in the image space or object space of the telecentric lens is less than 8° by setting the first hyperlens and the diaphragm on the same optical axis. The embodiment of the present application improves the telecentricity of the telecentric lens through the phase distribution of the superlens along the radial rotation symmetry of the superlens; and optimizes the phase distribution of the superlens by any formula in formulas (1) to (4). , thereby further improving the telecentricity of the telecentric lens. The metalens provided in the embodiment of the present application can withstand a laser power greater than 0.3W, and the utilization rate of light energy is greater than or equal to 75%. The telecentric lens provided by the embodiment of the present application has simple structure, small size, high imaging resolution, low mass production cost and high consistency; thus, the laser radar system including the telecentric lens has simple structure, small size and high imaging resolution. High, low mass production cost and high consistency.

The above is only the specific implementation of the embodiment of the present application, but the scope of protection of the embodiment of the present application is not limited thereto. Any person familiar with the technical field can easily Any changes or substitutions that come to mind should be covered within the protection scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application should be determined by the protection scope of the claims.

Claims (20)

1. A telecentric lens comprising a first hyperlens and an aperture; wherein,

   The first metalens includes a first planar substrate and a first nanostructure; wherein the first nanostructure is disposed on one side of the first planar substrate, and the first nanostructures are arranged periodically;

   Cooperating the diaphragm and the first hyperlens with the optical axis, so that the chief ray angle of the incident light in the object space or image space of the first hyperlens is less than 8°;

   And the aspect ratio of the first nanostructure is less than or equal to 20, so that the utilization rate of light energy of the first metalens is greater than or equal to 75%.
2. The telecentric lens according to claim 1, wherein the phase distribution of the first metalens is rotationally symmetric along the radial direction of the first metalens.
3. The telecentric lens according to claim 2, the phase of the first metalens at least satisfies any of the following formulas:

   

   

   Wherein, r is the distance from the center of the first hyperlens to any first nanostructure; (x, y) is the coordinate on the first hyperlens;

   

   is any constant phase; a _i is a coefficient, and a _i satisfies: in the expansion of the above formula, the coefficient of the first r ² or the first (x ² +y ² ) term is less than 0.
4. The telecentric lens according to claim 2, the phase of the first metalens at least satisfies any of the following formulas:

   

   

   Wherein, r is the distance from the center of the first hyperlens to any first nanostructure; (x, y) is the coordinate on the first hyperlens;

   

   is any constant phase; a _i is a coefficient, and a _i satisfies: in the expansion of the above formula, the coefficient of the first r ² term or the first (x ² +y ² ) term is less than 0.
5. The telecentric lens according to claim 1, wherein the distance between the aperture and the first metalens is less than or equal to one focal length of the first metalens.
6. The telecentric lens according to claim 1, wherein the aperture is located at the object focal plane of the first hyperlens, so that incident light passes through the aperture and the first hyperlens in sequence, and in the first hyperlens The chief ray angle of the image space of the metalens is less than 8°.
7. The telecentric lens according to claim 1, wherein the aperture is located at the focal plane of the image side of the first hyperlens, so that the incident light passes through the first hyperlens and the aperture sequentially and then exits in parallel.
8. The telecentric lens of claim 1, the first metalens further comprising a filling material; the filling material is filled between the first nanostructures.
9. The telecentric lens according to claim 1, wherein the periodic arrangement comprises a plurality of first superstructure units arranged in an array;

   The shape of the first superstructure unit includes close-packed graphics; the first superstructure unit is arranged on the surface of the first planar substrate;

   The first nanostructure is located at the apex and/or the center of the first superstructure unit.
10. The telecentric lens according to claim 1, wherein the height of the first nanostructure is greater than or equal to 300 nm and less than or equal to 3 μm.
11. The telecentric lens according to claim 1, wherein the arrangement period of the first nanostructure is greater than 300nm and less than 1500nm.
12. The telecentric lens according to claim 1, wherein the maximum full viewing angle of the telecentric lens is greater than or equal to 10° and less than or equal to 120°.
13. The telecentric lens according to claim 1, wherein the diameter of the first metalens is greater than or equal to 2mm and less than or equal to 50mm.
14. The telecentric lens according to claim 1, wherein the focal length of the first metalens is greater than or equal to 1 mm and less than or equal to 150 mm.
15. The telecentric lens according to claim 1, wherein the thickness of the first planar base is greater than or equal to 50 μm and less than or equal to 5 mm.
16. The telecentric lens of claim 1, further comprising a second metalens;

    Wherein, the second superlens includes a second planar substrate and a second nanostructure; the second nanostructure is disposed on one side of the second planar substrate, and the second nanostructures are arranged periodically;

    The second hyperlens is confocally arranged with the first hyperlens, so that the first hyperlens and the second hyperlens form a 4f optical system;

    The aperture is located at a confocal position of the second metalens and the first metalens.
17. A laser radar transmitting system, comprising a light source and the telecentric lens according to any one of claims 1-16;

    The light source is located on the object focal plane of the first metalens of the telecentric lens.
18. The laser radar transmitting system according to claim 17, the distance error between the light source and the focal plane is less than or equal to FD±2λF ² ;

    Wherein, FD is the focal depth of the system of the first hyperlens; F is the F number of the first hyperlens.
19. The laser radar transmitting system according to claim 18, the circumscribed circle radius R of the light source at least satisfies:

    R≤f ₁ tanθ

    Wherein, θ is the half angle of view of the first hyperlens; f ₁ is the focal length of the first hyperlens.
20. A laser radar receiving system, comprising a detector and the telecentric lens according to any one of claims 1-16;

    Wherein, the detector is located on the image-space focal plane of the first metalens of the telecentric lens.

Images