CN220671746U - Scanning laser beam expanding system and AR display device - Google Patents

Abstract

The utility model provides a scanning laser beam expanding system and an AR display device. The scanning laser beam expanding system comprises a laser emitting module, and an electromagnetic micro-vibration mirror, a beam expanding element and a collimating lens group which are sequentially arranged on the light emitting side of the laser emitting module, wherein the electromagnetic micro-vibration mirror is used for reflecting laser emitted by the laser emitting module onto the beam expanding element, and the beam expanding element is positioned at the object focal plane of the collimating lens group. The utility model solves the problems of large volume and small scanning field of view of the scanning laser beam expanding system in the prior art.

Description

Scanning laser beam expanding system and AR display device

Technical Field

The utility model relates to the technical field of optical imaging equipment, in particular to a scanning laser beam expanding system and an AR display device.

Background

The existing scanning laser beam expanding system based on the electromagnetic micro-vibrating mirror has the advantages of small size, high brightness and the like, so that the scanning laser beam expanding system becomes a very promising projection display scheme for realizing the lightening of the AR glasses, however, the scanning laser beam expanding system is limited by the size of the electromagnetic micro-vibrating mirror, the beam diameter cannot be very large, the phenomenon of carrying spots can occur after imaging through an AR waveguide, and the imaging quality is affected. Therefore, a beam-expanding relay system is required. However, this would make it difficult to make the volume of an AR projection engine based on Laser Beam Scanning (LBS) very small.

Currently common laser beam expanding systems are transmissive and reflective. The conventional transmission type beam expanding system has a kepler type beam expanding system with a positive lens combination and a galilean type beam expanding system with a positive lens combination. For a Galilean beam expanding system with a positive lens and a negative lens, a scanning galvanometer is positioned in front of a negative lens group, a positive lens group is positioned behind the negative lens, an object side focus of the positive lens group is required to coincide with the positive lens group, and the magnification of a light beam is equal to the focal length ratio of the positive lens group and the negative lens group. The system structure is limited by the focal length, and can not converge the light beams of each scanning field after beam expansion, which can not meet the requirement of waveguide coupling in AR glasses. The kepler type beam expanding system for positive and negative lens combinations has the magnification equal to the focal length ratio of the two lens groups, namely, the larger the magnification is, the longer the system is, so that the system is difficult to be small in size and is not suitable for being applied to wearing equipment which is light and small in the requirement of AR glasses.

In addition, the scan angle is inversely proportional to the magnification of the beam, i.e., the scan angle of the expanded beam system is reduced, as is the tension-invariant constraint. In order to meet the requirement of the view field of the AR glasses, the scanning angle of the electromagnetic micro-vibrating mirror needs to be increased, the view field of the AR glasses can be 40 degrees at present, when the laser beam is expanded by 2 times, namely the incident scanning view field is required to be 80 degrees, the scanning angle of the electromagnetic micro-vibrating mirror is 40 degrees, and the fast axis of the two-dimensional vibrating mirror is only 30 degrees and the slow axis is 24 degrees at present, so that the requirement is difficult to meet.

That is, the scanning laser beam expanding system in the prior art has the problems of large volume and small scanning field of view.

Disclosure of Invention

The utility model mainly aims to provide a scanning laser beam expanding system and an AR display device, which are used for solving the problems of large volume and small scanning field of view of the scanning laser beam expanding system in the prior art.

In order to achieve the above object, according to one aspect of the present utility model, there is provided a scanning laser beam expanding system, including a laser emitting module, and an electromagnetic micro-galvanometer, a beam expanding element and a collimating lens group sequentially disposed at a light emitting side of the laser emitting module, where the electromagnetic micro-galvanometer is used to reflect laser light emitted by the laser emitting module onto the beam expanding element, and the beam expanding element is located at an object focal plane of the collimating lens group.

Further, the laser emitting module includes: a laser array comprising at least three wavelengths of lasers; and the laser beam combiner is positioned on the light emitting side of the laser array.

Further, the laser array further comprises a laser collimation structure, wherein the laser collimation structure is positioned at an exit port of the laser.

Further, the electromagnetic micro-vibrating mirror is a two-dimensional electromagnetic micro-vibrating mirror, and the scanning field omega of the electromagnetic micro-vibrating mirror meets the following conditions: 10 ° < ω <30 °.

Further, the diameter of the electromagnetic micro-vibrating mirror is more than or equal to 0.7mm and less than or equal to 2mm; and/or the fast axis working frequency of the electromagnetic micro-vibrating mirror is larger than 20KHZ, and the slow axis working frequency is larger than 50HZ.

Further, the beam expanding element is a diffractive optical element or a light diffuser, and when the beam expanding element is a diffractive optical element, the light incident surface and/or the light emergent surface of the diffractive optical element are provided with a microstructure array, the microstructure array comprises a plurality of microstructures, and the size of each microstructure is more than or equal to 0.4 μm and less than or equal to 0.5 μm; when the beam expanding element is a light diffuser, the light incident surface and/or the light emergent surface of the light diffuser are/is provided with a plurality of micro lenses, the micro lenses on one surface are randomly distributed or periodically distributed, and the size of each micro lens is more than or equal to 2 mu m and less than or equal to 200 mu m.

Further, when the beam expanding element is a light diffuser, the light incident surface and the light emergent surface of the light diffuser are provided with a plurality of microlenses, and the surface shape of the microlenses on one surface comprises one or more of a spherical surface, an aspherical surface and a free-form surface.

Further, the collimating lens group includes a plurality of lenses, and the F-number of the collimating lens group satisfies: 0.866< f number <2.835.

Further, the distance between the electromagnetic micro-vibrating mirror and the beam expanding element is more than 3mm and less than 4mm; and/or the divergence angle of the beam expanding element is greater than 20 ° and less than 60 °; and/or the refractive index of the beam expanding element is greater than 1 and less than 5.

According to another aspect of the present utility model, there is provided an AR display device including: the scanning laser beam expanding system; the waveguide receiving module is provided with a coupling inlet, and the emitted light of the scanning laser beam expanding system is coupled into the waveguide receiving module through the coupling inlet.

By applying the technical scheme of the utility model, the scanning laser beam expanding system comprises a laser emitting module, and an electromagnetic micro-vibration mirror, a beam expanding element and a collimating lens group which are sequentially arranged on the light emitting side of the laser emitting module, wherein the electromagnetic micro-vibration mirror is used for reflecting laser emitted by the laser emitting module onto the beam expanding element, and the beam expanding element is positioned at the object focal plane of the collimating lens group.

The laser emitted by the laser emitting module is incident on the electromagnetic micro-vibrating mirror, the electromagnetic micro-vibrating mirror reflects the received laser to the beam expanding element, the laser enters the collimating lens group after being expanded and diffused by the beam expanding element, the collimating lens group collimates the divergent light beam and the laser light beams with different scanning fields are converged into the coupling port of the subsequent waveguide receiving module. By arranging the beam expanding system and the electromagnetic micro-vibrating mirror, the electromagnetic micro-vibrating mirror can realize deflection of laser, the beam expanding system is beneficial to realizing small volume, the aim of aligning a straight laser beam to expand and diverge is mainly realized, the spot-carrying phenomenon of subsequent imaging can be reduced, the beam expanding element is positioned at the object focal plane of the collimating lens group, the beam expanding multiple of the laser beam is only related to the divergence angle and the effective focal length of the collimating lens group, and the larger the divergence angle of the beam expanding element is, the smaller the required effective focal length of the collimating lens group is. Therefore, the total length of the collimating lens group can be effectively reduced by reasonably designing the divergence angle of the beam expanding element, thereby realizing the miniaturization of the scanning laser beam expanding system and simultaneously increasing the scanning field of view after beam expansion.

Drawings

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

FIG. 1 shows a schematic light path diagram of an AR display device according to an alternative embodiment of the present utility model;

fig. 2 shows a schematic structural diagram of the laser emitting module in fig. 1;

FIG. 3 shows a schematic view of the optical path of the beam expanding element of FIG. 1 as a diffractive optical element;

FIG. 4 shows a schematic diagram of the structure of the diffractive optical element in FIG. 3;

FIG. 5 shows a schematic view of the light path of the beam expanding element of FIG. 1 as a light diffuser;

FIG. 6 shows a schematic view of the light diffuser of FIG. 5;

fig. 7 shows a schematic view of the optical path of the collimator lens set in fig. 1.

Wherein the above figures include the following reference numerals:

10. a laser emitting module; 11. an array of lasers; 12. a laser beam combiner; 20. an electromagnetic micro-vibrating mirror; 30. a beam expanding element; 31. a diffractive optical element; 311. a microstructure array; 32. a light diffuser; 321. a microlens; 322. a substrate; 40. a collimating lens group; 41. an object focal plane; 42. an object plane; 43. an image-side principal plane; 44. an image focal plane; 50. a waveguide receiving module.

Detailed Description

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The utility model will be described in detail below with reference to the drawings in connection with embodiments.

It is noted that all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs unless otherwise indicated.

In the present utility model, unless otherwise indicated, terms of orientation such as "upper, lower, top, bottom" are used generally with respect to the orientation shown in the drawings or with respect to the component itself in the vertical, upright or gravitational direction; also, for ease of understanding and description, "inner and outer" refers to inner and outer relative to the profile of each component itself, but the above-mentioned orientation terms are not intended to limit the present utility model.

In order to solve the problems of large volume and small scanning field of view of a scanning laser beam expanding system in the prior art, the utility model provides the scanning laser beam expanding system and an AR display device.

As shown in fig. 1 to 7, the scanning laser beam expanding system includes a laser emitting module 10, and an electromagnetic micro-oscillating mirror 20, a beam expanding element 30 and a collimating lens group 40 sequentially disposed on the light emitting side of the laser emitting module 10, where the electromagnetic micro-oscillating mirror 20 is used to reflect the laser emitted by the laser emitting module 10 onto the beam expanding element 30, and the beam expanding element 30 is located at an object focal plane 41 of the collimating lens group 40.

The laser emitted by the laser emitting module 10 is incident on the electromagnetic micro-vibrating mirror 20, the electromagnetic micro-vibrating mirror 20 reflects the received laser to the beam expanding element 30, the laser enters the collimating lens group 40 after being expanded and diffused by the beam expanding element 30, the collimating lens group 40 collimates the divergent beam and merges the laser beams with different scanning fields into the coupling inlet of the subsequent waveguide receiving module 50. By arranging the beam expanding system and the electromagnetic micro-vibrating mirror 20, the electromagnetic micro-vibrating mirror 20 can realize deflection of laser, which is beneficial to realizing small volume, the beam expanding system mainly realizes the purpose of carrying out beam expanding and diverging on the aligned laser beams, the spot-carrying phenomenon of subsequent imaging can be reduced, the beam expanding element 30 is positioned at the object focal plane 41 of the collimating lens group 40, the beam expanding multiple of the laser beams is only related to the divergence angle and the effective focal length of the collimating lens group 40, and the larger the divergence angle of the beam expanding element 30 is, the smaller the required effective focal length of the collimating lens group 40 is. Therefore, by reasonably designing the divergence angle of the beam expanding element 30, the total length of the collimator lens group 40 can be effectively reduced, thereby realizing miniaturization of the scanning laser beam expanding system and increasing the scanning field of view after beam expansion.

As shown in fig. 2, the laser emitting module 10 includes a laser array 11 and a laser beam combiner 12, and the laser array 11 includes at least three wavelength lasers; the laser combiner 12 is located on the light exit side of the laser array 11. The wavelength range of the laser array 11 of the laser emitting module 10 of the present application satisfies 450nm or more and 680nm or less. The laser array 11 is composed of lasers with R, G, B three wavelengths, light with R, G, B three wavelengths in the laser array 11 changes the lighting sequence, time, power and the like according to driving, and then the light beams with the required colors are synthesized by the laser beam combiner 12 to be emitted, and the light beams with the required colors for scanning the laser beam expanding system are emitted. The diameter of the finally emitted light beam is smaller than 1mm.

Specifically, the laser array 11 further includes a laser collimation structure, where the laser collimation structure is located at an exit port of a single laser, and the exit ports of the three lasers may be respectively provided with a laser collimation structure, where the laser collimation structure is composed of a fast axis collimation mirror and a slow axis collimation mirror. By providing a laser collimation structure, the divergent light beam is collimated, and the light beam enters the laser combiner 12.

In the specific embodiment of the present application, the electromagnetic micro-vibrating mirror 20 is a two-dimensional electromagnetic micro-vibrating mirror, specifically a circular reflecting mirror, and the scan field ω of the electromagnetic micro-vibrating mirror 20 satisfies: 10 ° < ω <30 °. The diameter of the electromagnetic micro-vibrating mirror 20 is more than or equal to 0.7mm and less than or equal to 2mm; the electromagnetic micro-vibrating mirror 20 has a fast axis operating frequency greater than 20KHZ and a slow axis operating frequency greater than 50HZ. The electromagnetic micro-vibrating mirror 20 is used as a reflection module of a scanning laser beam expanding system to realize two-dimensional high-frequency vibration in the X direction and the Y direction, and reflects the incident laser beam according to the specified algorithm requirement. The electromagnetic micro-mirrors 20 scan at a frequency that is higher than the refresh rate 20HZ of the human eye, so that the image scanned and reflected by the electromagnetic micro-mirrors 20 is a continuous image in the human eye. In addition, since scanning imaging is performed by using the electromagnetic micro-vibrator 20, focusing is not required, and imaging can be performed at any position, the beam expanding element 30 for receiving the reflected beam of the electromagnetic micro-vibrator 20 can be infinitely close to the electromagnetic micro-vibrator 20, and thus the distance from the electromagnetic micro-vibrator 20 to the beam expanding element 30 can be small, thereby achieving miniaturization of the scanning laser beam expanding system.

In the specific embodiment of the present application, the beam expanding element 30 is a diffractive optical element 31 (DOE) or a light Diffuser 32 (Diffuser), and the distance between the electromagnetic micro-vibrating mirror 20 and the beam expanding element 30 is greater than 3mm and less than 4mm. The beam expander 30 is used for realizing beam diffusion, and diffuses the laser beam reflected by the electromagnetic micro-oscillator 20 into a divergent beam with a certain divergence angle, and the divergence angle is determined by the specific structural design of the beam expander 30. The beam expander 30 can emit light beams with different scanning angles at an angle close to 0 degrees, and the effect is shown by the front and back light rays of the beam expander 30 in fig. 1. The divergence angle of the beam expanding element 30 of the present application satisfies more than 20 ° and less than 60 °; the beam expanding element 30 is composed of base glass and glue, and the structure on the surface is made by using a photoetching or nano-imprinting mode, and the thickness of the beam expanding element 30 is generally smaller than 2mm. The size H of the beam expanding element 30 is determined by the distance d of the beam expanding element 30 to the electromagnetic micro-vibrating mirror 20 and the scan field ω of the electromagnetic micro-vibrating mirror 20, and the size H of the beam expanding element 30, the distance d of the beam expanding element 30 to the electromagnetic micro-vibrating mirror 20, and the scan field ω of the electromagnetic micro-vibrating mirror 20 satisfy the relation h=d×tan (ω/2), so the size H of the beam expanding element 30 is <1.6mm.

Specifically, when the beam expander 30 is the diffractive optical element 31, only the light incident surface of the diffractive optical element 31 has the microstructure array 311, or only the light emergent surface of the diffractive optical element 31 has the microstructure array 311, or both the light incident surface and the light emergent surface of the diffractive optical element 31 have the microstructure array 311, which can be selected according to practical situations. The microstructure array 311 includes a plurality of microstructures, the positions, heights, sizes, and shapes of which are different, wherein each microstructure is in the order of micrometers, and the size of each microstructure is 0.4 μm or more and 0.5 μm or less. Through the design of the position, the height, the size and the shape of each microstructure, the purpose of the divergence and the emergence of the incident parallel light with different angles can be realized, and the divergence angle can be accurately controlled through the design.

As shown in fig. 3 and 4, an optical path schematic view and a structural schematic view of the diffractive optical element 31 in practical use are shown, respectively. As can be seen from the figure, only the light incident surface of the diffractive optical element 31 has the microstructure array 311, and the microstructure array 311 is composed of convex or concave microstructures, and the light emergent surface of the diffractive optical element 31 is a plane. Referring to fig. 4, a beam of a specified divergence angle can be obtained due to the different designs of the shape, position, and height of each microstructure.

Specifically, when the beam expander 30 is the light diffuser 32, only the light incident surface of the light diffuser 32 has a plurality of microlenses 321, only the light emergent surface of the light diffuser 32 has a plurality of microlenses 321, or both the light incident surface and the light emergent surface of the light diffuser 32 have a plurality of microlenses 321, which can be designed according to the actual angle requirement. The microlenses 321 on one surface are randomly distributed or periodically distributed, and each microlens 321 has a size on the order of micrometers, and each microlens 321 has a size of 2 μm or more and 200 μm or less.

As shown in fig. 5 and 6, an optical path schematic view and a structural schematic view of the light diffuser 32 are respectively shown in practical use. In the embodiment of the present application, according to the beam expanding requirement, the light incident surface and the light emergent surface of the light diffuser 32 are respectively provided with a plurality of microlenses 321, and the plurality of microlenses 321 of the light incident surface and the plurality of microlenses 321 of the light emergent surface are randomly arranged, and the microlenses 321 of the two surfaces are respectively arranged on the two side surfaces of the substrate 322. The surface shape of the plurality of microlenses 321 on one surface includes one of a spherical surface, an aspherical surface, and a free-form surface. By designing the surface shape, position, height, thickness and relative positions of the two sides of each microlens 321, the purpose of emitting the parallel light of different incident angles reflected by the electromagnetic micro-vibrating mirror 20 according to the required divergence angle is achieved.

As shown in fig. 7, the collimator lens group 40 includes a plurality of lenses including at least two biconvex lenses having optical power, and the two biconvex lenses include a spherical mirror and an aspherical mirror. The collimating lens group 40 is a transmissive telecentric lens, and can expand the light beams at each scanning angle and then enter the waveguide after converging at the coupling port of the waveguide receiving module 50. The image-side focal plane 44 of the collimating lens group 40 is located at the coupling-in port of the waveguide receiving module 50, and the object-side focal plane 41 of the collimating lens group 40 is located at the convergence point of the diverging beams of the beam expanding element 30. The image height h 'of the collimator lens group 40 is related to the scan field ω of the electromagnetic micro-vibrator 20 and the distance d of the electromagnetic micro-vibrator 20 from the beam expander 30, satisfying the relation h' =d×tan (ω/2). The focal length f of the collimator lens group 40 is related to the beam expansion diameter D and the divergence angle θ of the beam expansion system, satisfying the relation d=2f×tan (θ/2). This design enables the collimator lens group 40 to collimate the divergent light beam having a divergence angle θ exiting from the beam expanding element 30, and finally the light beams incident at different heights are finally collimated and converged into the coupling port. Since the divergence angle θ of the beam expanding element 30 satisfies: 20 ° < θ <60 °, the F-number of the collimator lens group 40 satisfies: 0.866< f number <2.835. The aim of controlling the scan field of view of the beam exiting the beam expander 30 can be achieved by the cooperation of the image height and the effective focal length of the collimator lens group 40 to meet the field of view required in AR glasses.

As shown in fig. 7, the collimator lens group 40 has, in order from the object side to the image side, an object-side focal plane 41, an object-side principal plane 42, an image-side principal plane 43, and an image-side focal plane 44. The object focal plane 41 is a plane in which the convergence point of the reverse extension lines of the divergent light beams is located after all divergences by the beam expanding element 30. The convergence point of the diverging light beam of the beam expanding element 30 is located on the object focal plane 41 of the collimating lens group 40, i.e. the distance d from the object focal plane 41 to the object principal plane 42 of the collimating lens group 40 is equal to the object focal length f of the collimating lens group 40, so as to achieve collimation of the diverging light beam. The coupling-in opening is located on the image-side focal plane 44, i.e. the distance d of the coupling-in opening from the image-side principal plane 43 of the collimating lens group 40 is equal to the image Fang Jiaoju f' of the collimating lens group 40, so that all the light beams of the scan-field eventually enter the coupling-in opening of the waveguide receiving module 50.

Specifically, the refractive index of the beam expanding element 30 is greater than 1 and less than 5. By the refractive index and the surface shape of each micro unit of the beam expanding element 30, a desired divergence angle can be obtained according to the law of refraction and the law of diffraction, thereby achieving a desired beam expansion.

In summary, the scanning laser beam expanding system of the present application has at least the following advantages:

1. by the design of the beam expanding element 30 and the collimator lens group 40, the effects of collimation and expansion of the light beam can be achieved. To realize the function of pupil expansion applied in a laser scanning (LBS) optical machine.

2. By the diffusion design of the beam expanding element 30 on the collimated laser beam, the volume of the transmission beam expanding system can be reduced, and the purpose of lightening the laser scanning (LBS) optical machine in the head-mounted equipment such as AR glasses is achieved.

3. The method can break through the limitation of the Lach invariant in the traditional laser transmission beam expanding system, realize beam expansion, simultaneously meet the required view field of an AR optical machine, and reduce the deflection angle requirement on the electromagnetic micro-vibrating mirror 20.

As shown in fig. 1, the present application further provides an AR display device, including the scanning laser beam expanding system and the waveguide receiving module 50, where the waveguide receiving module 50 has a coupling port, the scanning laser beam expanding system emits light, which is coupled into the waveguide receiving module 50 through the coupling port, and the coupling port of the waveguide receiving module 50 is located at the image focal plane 44 of the collimating lens group 40. By adopting the scanning laser beam expanding system which has small volume and can realize real image laser beam expanding collimation, the spot-carrying phenomenon of the AR display device is greatly reduced, and the imaging quality is improved.

It should be noted that the scanning laser beam expanding system of the present application is mainly applied to a laser scanning (LBS) optical machine, and the above-mentioned AR display device may be, but is not limited to, AR glasses.

It will be apparent that the embodiments described above are merely some, but not all, embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present utility model without making any inventive effort, shall fall within the scope of the present utility model.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the present application described herein may be implemented in sequences other than those illustrated or described herein.

The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims (10)

1. The scanning laser beam expanding system is characterized by comprising a laser emitting module (10) and an electromagnetic micro-vibration mirror (20), a beam expanding element (30) and a collimating lens group (40) which are sequentially arranged on the light emitting side of the laser emitting module (10), wherein the electromagnetic micro-vibration mirror (20) is used for reflecting laser emitted by the laser emitting module (10) onto the beam expanding element (30), and the beam expanding element (30) is positioned at an object space focal plane (41) of the collimating lens group (40).

2. The scanning laser beam expanding system according to claim 1, wherein the laser emitting module (10) comprises:

-a laser array (11), the laser array (11) comprising at least three wavelength lasers;

and the laser beam combiner (12), wherein the laser beam combiner (12) is positioned on the light emitting side of the laser array (11).

3. A scanning laser beam expanding system according to claim 2, wherein the laser array (11) further comprises a laser collimating structure located at the exit port of the laser.

4. The scanning laser beam expanding system according to claim 1, wherein the electromagnetic micro-vibrating mirror (20) is a two-dimensional electromagnetic micro-vibrating mirror, and the scanning field of view ω of the electromagnetic micro-vibrating mirror (20) satisfies: 10 ° < ω <30 °.

5. The scanning laser beam expanding system according to claim 1, wherein,

the diameter of the electromagnetic micro-vibrating mirror (20) is more than or equal to 0.7mm and less than or equal to 2mm; and/or

The fast axis working frequency of the electromagnetic micro-vibrating mirror (20) is larger than 20KHZ, and the slow axis working frequency is larger than 50HZ.

6. A scanning laser beam expanding system according to claim 1, wherein the beam expanding element (30) is a diffractive optical element (31) or a light diffuser (32),

when the beam expanding element (30) is a diffraction optical element (31), a microstructure array (311) is arranged on the light incident surface and/or the light emergent surface of the diffraction optical element (31), the microstructure array (311) comprises a plurality of microstructures, and the size of each microstructure is more than or equal to 0.4 mu m and less than or equal to 0.5 mu m;

when the beam expanding element (30) is a light diffuser (32), the light incident surface and/or the light emergent surface of the light diffuser (32) are provided with a plurality of micro lenses (321), the micro lenses (321) on one surface are randomly distributed or periodically distributed, and the size of each micro lens (321) is more than or equal to 2 mu m and less than or equal to 200 mu m.

7. The scanning laser beam expanding system according to claim 6, wherein when the beam expanding element (30) is a light diffuser (32), the light entrance surface and the light exit surface of the light diffuser (32) each have a plurality of microlenses (321), and the surface shape of the plurality of microlenses (321) on one surface includes one or more of a spherical surface, an aspherical surface, and a free-form surface.

8. The scanning laser beam expanding system according to claim 1, wherein the collimator lens group (40) comprises a plurality of lenses, the collimator lens group (40) having an F-number satisfying: 0.866< f number <2.835.

9. The scanning laser beam expanding system according to any one of claims 1 to 8, wherein,

the distance between the electromagnetic micro-vibrating mirror (20) and the beam expanding element (30) is more than 3mm and less than 4mm; and/or

The divergence angle of the beam expanding element (30) is more than 20 degrees and less than 60 degrees; and/or

The refractive index of the beam expanding element (30) is greater than 1 and less than 5.

10. An AR display device, comprising:

the scanning laser beam expanding system of any of claims 1 to 9;

-a waveguide receiving module (50), the waveguide receiving module (50) having a coupling-in port from which the scanning laser beam expanding system emitted light is coupled into the waveguide receiving module (50).