Speckle reduction optical path structure and laser projection device

Abstract

A speckle reduction optical path structure and a laser projection device. The speckle reduction optical path structure comprises: a laser light source (1), used for emitting a laser beam; a speckle reduction element (2), used for transmitting the laser beam emitted by the laser light source (1); and a reflecting optical path assembly (3), comprising reflecting surfaces (30). The laser beam emitted by the laser light source (1) enters the speckle reduction element (2) and then reaches a reflecting surface (30), and is reflected by the reflecting surfaces (30) to enter the speckle reduction element (2). The laser beam emitted by the laser light source (1) passes through the speckle reduction element (2) at least twice in the process of changing directions by means of the reflecting surfaces (30) of the reflecting optical path assembly (3) so as to suppress speckles of the laser beam at least twice, and exits the speckle reduction element (2). The laser beam exiting the speckle reduction element (2) exits same, with the optical axis of the laser beam forming an included angle of 60° to 90° with the surface of the speckle reduction element (2), and then enters the subsequent optical path.

Description

Speckle elimination optical path structure and laser projection equipment

[0001] Citation of Related Applications

[0002] This disclosure claims all rights and interests in the invention patent application with application number 202410123101.1, entitled “Speckle Eliminating Optical Path Structure and Laser Projection Device”, filed with the State Intellectual Property Office of the People’s Republic of China on January 29, 2024; and the utility model patent application with application number 202420224948.4, entitled “Speckle Eliminating Optical Path Structure and Laser Projection Device”, and incorporates all of them into this disclosure by reference.

[0003] field

[0004] The present disclosure relates to the field of projection display technology, and in particular to a speckle elimination optical path structure and a laser projection device.

[0005] background

[0006] As a new generation of projection light source, laser has the characteristics of high brightness, good monochromaticity and small luminous angle. However, due to the high coherence of laser, projection products using laser are usually accompanied by speckle phenomenon, which affects the consumer experience.

[0007] Overview

[0008] In a first aspect, the present disclosure provides a speckle-eliminating optical path structure, comprising: a laser light source configured to emit a laser beam; a speckle-eliminating element configured to transmit the laser beam emitted by the laser light source; and a reflective optical path assembly including a reflective surface, wherein the laser beam emitted by the laser light source enters the speckle-eliminating element and reaches the reflective surface, where it is reflected by the reflective surface and enters the speckle-eliminating element. During the process of changing direction by the reflective surface of the reflective optical path assembly, the laser beam emitted by the laser light source passes through the speckle-eliminating element at least twice, thereby suppressing speckle of the laser beam at least twice, and then is emitted from the speckle-eliminating element. The optical axis of the laser beam emitted from the speckle-eliminating element is emitted at an angle of 60° to 90° with the surface of the speckle-eliminating element before entering a subsequent optical path.

[0009] In some embodiments, a reflective optical path component is disposed on a side of the speckle reduction element away from the laser light source, and includes a first reflective surface and a second reflective surface disposed at a preset angle. A laser beam emitted by the laser light source passes through the speckle reduction element for the first time, is incident on the first reflective surface, is reflected by the first reflective surface to the second reflective surface, and then, after being reflected by the second reflective surface, passes through the speckle reduction element for a second time and is emitted.

[0010] In some embodiments, the angle between the optical axis of the laser beam when it passes through the speckle reducing element for the first time and the surface of the speckle reducing element ranges from 60° to 90°.

[0011] In some embodiments, the angle formed by the normal of the first reflective surface and the surface of the speckle reducing element is in the range of 45°±15°; and the angle formed by the normal of the second reflective surface and the surface of the speckle reducing element is in the range of 45°±15°.

[0012] In some embodiments, at least one of the first reflective surface and the second reflective surface is a flat surface or a curved surface, and the curved surface is a concave surface.

[0013] In some embodiments, the concave surface is any one of a spherical surface, an even-order aspherical surface, or a free-form surface.

[0014] In some embodiments, the first reflective surface and the second reflective surface are further provided with a reflective film.

[0015] In some embodiments, the reflective optical path assembly includes a first reflector and a second reflector disposed at a preset angle, wherein the first reflector is provided with a first reflective surface, and the second reflector is provided with a second reflective surface.

[0016] In some embodiments, the reflective optical path component includes a prism, which includes a first reflective surface, a second reflective surface, and a transmissive surface connecting the first reflective surface and the second reflective surface, and the transmissive surface is arranged toward the despeckle element.

[0017] In some embodiments, the speckle reduction optical path structure further includes a driving mechanism, the speckle reduction element is a diffusion wheel, and a power output end of the driving mechanism is coaxially arranged with the diffusion wheel to drive the diffusion wheel to rotate.

[0018] In some embodiments, the speckle-reducing element is a disk structure, and its diameter d ranges from 20 mm to 60 mm.

[0019] In some embodiments, the minimum distance between the speckle reduction element and the reflective optical path component is 0.1d-2d.

[0020] In some embodiments, a half-wave plate is further provided on a side of the speckle reducing element facing the laser light source, and the half-wave plate and the speckle reducing element are coaxially arranged and connected as a whole.

[0021] In some embodiments, the speckle optical path structure further includes a driving mechanism, the speckle elimination element is a vibrating diffuser, and the driving mechanism drives the vibrating diffuser to vibrate in any one of the XY plane, the YZ plane, and the XZ plane.

[0022] In some embodiments, the vibration diffuser is rectangular in shape, and a diagonal dimension L thereof ranges from 20 mm to 60 mm.

[0023] In some embodiments, the minimum distance between the vibrating diffuser and the reflective light path component is 0.1L to 2L.

[0024] In a second aspect, the present disclosure provides a laser projection device, comprising: the speckle-eliminating optical path structure described in the present disclosure; an image display device and a first lens assembly, the first lens assembly being arranged between the reflective optical path assembly of the speckle-eliminating optical path structure and the image display device, and configured to converge the laser beam from the speckle-eliminating optical path structure to the image display device to form an illumination spot; and a lens configured to project image information emitted from the image display device onto a screen.

[0025] In some embodiments, a reflective optical path component is disposed on a side of the speckle eliminating element away from the laser light source, and includes a first reflective surface and a second reflective surface disposed at preset angles; the laser projection device further includes: a second lens component disposed between the laser light source and the speckle eliminating element of the speckle eliminating element, and configured to focus the laser beam on the speckle eliminating element; a third lens component disposed between the speckle eliminating element and the reflective optical path component, and configured to diverge the laser beam focused on the speckle eliminating element and make it incident on the first reflective surface of the reflective optical path component, the laser beam from the first reflective surface being emitted via the second reflective surface and entering the third lens component again, and then converging and entering the speckle eliminating element again; a homogenizing component disposed between the reflective optical path component and the first lens component, and configured to homogenize and shape the laser beam emitted from the speckle eliminating element.

[0026] In some embodiments, the light homogenizing assembly includes a fly-eye lens and a fourth lens assembly, wherein the fourth lens assembly is disposed between the speckle reducing element and the fly-eye lens and is configured to collimate the laser beam emitted from the speckle reducing element.

[0027] In some embodiments, the light homogenizing component is a quadrilateral column, and its cross-section is rectangular or trapezoidal.

[0028] The present disclosure provides a speckle reduction optical path structure and a laser projection device. The speckle reduction optical path structure includes: a laser light source, a speckle reduction element, and a reflective optical path assembly. A laser beam emitted by the laser light source enters the speckle reduction element, reaches a reflective surface, and is reflected by the reflective surface into the speckle reduction element. During the process of changing direction by the reflective surface of the reflective optical path assembly, the laser beam passes through the speckle reduction element at least twice, thereby suppressing the laser beam's speckle at least twice, and then exits the speckle reduction element. Thus, in some embodiments, the reflective surface of the reflective optical path assembly can change the direction of the laser beam, causing the laser beam to pass through the speckle reduction element at least twice, thereby suppressing the laser beam's speckle at least twice, effectively improving the laser beam's speckle reduction effect. In some embodiments, the optical axis of the laser beam emitted from the speckle reduction element exits at an angle of 60°-90° with the surface of the speckle reduction element before entering the subsequent optical path. This improves light efficiency and shortens the overall length of the projection optical path. When applied to a laser projection device, this speckle reduction optical path structure is compact, lightweight, highly mobile, and easily portable, making it widely suitable for travel and business. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without inventive work. In addition, in the drawings, the same reference numerals are used for the same components, and the drawings are not drawn according to the actual scale.

[0030] FIG1 is a schematic structural diagram of a speckle elimination optical path structure provided by an embodiment of the present disclosure;

[0031] FIG2 is a schematic structural diagram of a speckle elimination optical path structure provided by another embodiment of the present disclosure;

[0032] FIG3 is a schematic structural diagram of a speckle elimination optical path structure provided by another embodiment of the present disclosure;

[0033] FIG4 is a schematic structural diagram of a speckle elimination optical path structure provided by another embodiment of the present disclosure;

[0034] FIG5 is a schematic structural diagram of a speckle elimination optical path structure provided by another embodiment of the present disclosure;

[0035] FIG6 is a schematic structural diagram of a speckle elimination optical path structure provided by another embodiment of the present disclosure;

[0036] FIG7 is a schematic structural diagram of a speckle elimination optical path structure provided by another embodiment of the present disclosure;

[0037] FIG8 is a schematic structural diagram of a speckle elimination optical path structure provided by another embodiment of the present disclosure;

[0038] FIG9 is a schematic structural diagram of a laser projection device provided by an embodiment of the present disclosure;

[0039] FIG10 is a schematic structural diagram of a light homogenization component of the laser projection device shown in FIG9 ;

[0040] FIG11 is a schematic structural diagram of another light homogenizing component of the laser projection device shown in FIG9 .

[0041] Explanation of the accompanying symbols: 1. Laser light source; R, red laser; G, green laser; B, blue laser; 2. Speckle elimination element; 22. Driving mechanism; 23. Half-wave plate; 3. Reflective optical path component; 30. Reflective surface; 31. First reflection surface; 32. Second reflection surface; 33. Reflective film; 3a. First reflection mirror; 3b. Second reflection mirror; 34. Transmission surface; 4. Light combining component; 5. Second lens component; 6. Third lens component; 7. Light homogenization component; 71. Compound eye lens; 72. Fourth lens component; 73. Square rod; 8. First lens component; 9. Image display device; 10. Lens.

[0042] Details

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0044] As shown in FIG1 , an embodiment of the present disclosure provides a speckle reduction optical path structure, comprising: a laser light source 1 , a speckle reduction element 2 , and a reflective optical path component 3 .

[0045] The laser light source 1 includes at least one of a red laser R, a green laser G, and a blue laser B. The laser light source 1 is used to emit a laser beam, which has the characteristics of high brightness, good monochromaticity, a small luminous angle, and high coherence. The high coherence of the laser can cause a speckle effect in laser projection display. The speckle effect refers to the situation where, when a coherent light source is irradiated on an optically rough surface with an average fluctuation greater than the laser wavelength, such as a wall, paper, or frosted glass, the scattered light interferes in space due to a constant phase difference, the same light wave frequency, and consistent vibration direction. Some parts of the interference are constructive, while others are destructive, resulting in a random spatial light intensity distribution and a granular structure. The end result is the appearance of alternating light and dark spots on the screen, also known as speckle. These unfocused spots appear flickering to the human eye, which can easily cause discomfort if viewed for a long time. This can seriously affect the quality of the projected image and reduce the user's viewing experience.

[0046] Speckle reduction element 2 is used to transmit the laser beam emitted by laser light source 1 to suppress laser speckle. Speckle reduction element 2 includes, but is not limited to, components that can diffuse the beam or change its angle, such as a vibrating diffuser, a rotating diffuser wheel, and a diffractive optical device. Speckle reduction element 2 can be either static or dynamic.

[0047] Reflective optical path assembly 3 includes a reflective surface. After entering speckle-eliminating element 2, the laser beam emitted by laser light source 1 reaches the reflective surface, where it is reflected by the reflective surface and then enters speckle-eliminating element 2. During the process of changing direction through the reflective surface of reflective optical path assembly 3, the laser beam emitted by laser light source 1 passes through speckle-eliminating element 2 at least twice, thereby suppressing the speckle of the laser beam at least twice. The laser beam then exits speckle-eliminating element 2. The optical axis of the laser beam exiting speckle-eliminating element 2 exits at an angle of 60° to 90° with the surface of speckle-eliminating element 2 before entering the subsequent optical path. That is, the angle between the optical axis of the laser beam exiting speckle-eliminating element 2 and the normal to the speckle-eliminating element 2 ranges from 0° to 30°. The subsequent optical path is the optical path that the laser beam enters after exiting the speckle-eliminating optical path structure. It may include optical components such as a focusing lens, a light homogenizing assembly, an image display device, and a lens.

[0048] In the disclosed embodiment, the reflective surface of reflective optical path assembly 3 is used to redirect the laser beam, allowing the laser beam, after being reflected by the reflective surface, to pass through speckle-reducing element 2 multiple times. Each time the laser beam passes through speckle-reducing element 2, its speckle is suppressed. Multiple passes through speckle-reducing element 2 suppress the laser beam's speckle multiple times. This ensures that when the laser beam emitted from speckle-reducing element 2 is projected onto the screen via subsequent optical paths, the laser speckle contrast meets the product's usage requirements, achieving an optimal speckle effect. Furthermore, multiple passes through the same speckle-reducing element 2 for multiple speckle suppression shorten the overall length of the projection optical path, reduce the number of speckle-reducing elements 2, and significantly lower production costs.

[0049] Furthermore, the speckle-eliminating element 2 can be a rectangular block of uniform thickness or a wedge-shaped block of unequal thickness. The laser beam is incident or emitted along the thickness direction of the speckle-eliminating element 2. The angle between the optical axis of the laser beam emitted from the speckle-eliminating element 2 and the surface of the speckle-eliminating element 2 is in the range of 60° to 90°. While minimizing the overall volume of the speckle-eliminating optical path structure, the emitted laser beam can be incident on other optical elements in the subsequent optical path substantially symmetrically about the optical axis without affecting the collection efficiency of the subsequent laser beam. For example, this can improve the light converging effect of the subsequent lens assembly used for light collection. For another example, when passing through the light homogenizer, the uniformity of the displayed image can be improved, thereby enhancing the optical efficiency of the speckle-eliminating optical path structure.

[0050] The speckle reduction optical path structure provided by the disclosed embodiments includes a laser light source 1, a speckle reduction element 2, and a reflective optical path component 3. The laser beam emitted by laser light source 1 enters the speckle reduction element 2, reaches a reflective surface, and is reflected by the reflective surface into the speckle reduction element 2. During the process of changing direction by the reflective surface of the reflective optical path component 3, the laser beam emitted by laser light source 1 passes through the speckle reduction element 2 at least twice, thereby suppressing the speckle of the laser beam at least twice, and then exits from the speckle reduction element 2. Thus, the reflective surface of the reflective optical path component 3 changes the direction of the laser beam, causing the laser beam to pass through the speckle reduction element 2 at least twice, thereby suppressing the laser beam's spot at least twice. This effectively improves the speckle reduction effect of the laser beam and shortens the overall length of the projection optical path. Furthermore, the optical axis of the laser beam emitted from the speckle reduction element 2 exits at an angle of 60° to 90° with the surface of the speckle reduction element 2 before entering the subsequent optical path. This improves the optical efficiency of the speckle reduction optical path structure and, in turn, enhances the uniformity of image display.

[0051] The specific structure of the speckle elimination optical path structure provided by the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0052] In some embodiments, the reflective optical path component 3 is disposed on a side of the speckle-eliminating element 2 away from the laser light source 1 and includes a first reflective surface 31 and a second reflective surface 32 arranged at preset angles. After passing through the speckle-eliminating element 2 for the first time, the laser beam emitted by the laser light source 1 is incident on the first reflective surface 31, reflected by the first reflective surface 31 to the second reflective surface 32, and then reflected by the second reflective surface 32. After passing through the speckle-eliminating element 2 for a second time, the laser beam is emitted.

[0053] As shown in Figure 1, first reflective surface 31 is located on the optical axis of the laser beam initially emitted from speckle-combating element 2, while second reflective surface 31 is located on the optical axis of the laser beam that re-enters speckle-combating element 2. First reflective surface 31 and second reflective surface 32 are arranged at a preset angle. The laser beam that initially passes through speckle-combating element 2 changes direction via first reflective surface 31 and second reflective surface 32 before returning to speckle-combating element 2. In this way, the laser beam emitted by laser light source 1 passes through the same speckle-combating element 2 twice, suppressing the laser beam's speckle twice and improving the laser's speckle reduction effect.

[0054] Furthermore, this method of providing a first reflective surface 31 and a second reflective surface 32 on the side of the speckle-eliminating element 2 facing away from the laser light source to reflect the laser beam twice ensures symmetry between the laser beam entering the speckle-eliminating element 2 and the laser beam exiting from it. This ensures that the speckle reduction effect is the same each time the laser beam passes through the speckle-eliminating element 2, resulting in stable and controllable optical efficiency. Furthermore, the laser beam that first passes through the speckle-eliminating element 2 and the laser beam that ultimately exits the speckle-eliminating element 2 are located on the same side of the speckle-eliminating element 2, thereby offsetting or partially offsetting the overall length of the subsequent optical path structure and the speckle-eliminating optical path structure. This helps shorten the overall length of the projection optical path and ultimately reduces the volume of the entire speckle-eliminating optical path structure.

[0055] In some embodiments, the angle formed between the optical axis of the laser beam when it first passes through the speckle-eliminating element 2 and the surface of the speckle-eliminating element 2 is within a range of 60° to 90°. In other words, the angle formed between the optical axis of the laser beam when it first passes through the speckle-eliminating element 2 and the surface of the speckle-eliminating element 2 and the angle formed between the optical axis of the laser beam emitted from the speckle-eliminating element 2 and the surface of the speckle-eliminating element 2 are within the same range. This ensures that the optical axis of the incident laser beam entering the speckle-eliminating element 2 and the optical axis of the outgoing laser beam remain symmetrical, achieving the same speckle reduction effect each time it passes through the speckle-eliminating element 2, and maintaining stable and controllable optical efficiency. Furthermore, the projection optical path of the speckle-eliminating optical path structure can be kept as short as possible, resulting in a compact overall structure.

[0056] In some examples, as shown in FIG1 , the angle formed between the optical axis of the laser beam when it first passes through the speckle reducing element 2 and the surface of the speckle reducing element 2 is 90°, and the angle formed between the optical axis of the laser beam after being reflected by the reflective optical path component 3 and the surface of the speckle reducing element 2 is also 90°. That is, the angle formed between the optical axis of the laser beam when it first passes through the speckle reducing element 2 and the normal of the speckle reducing element 2 is 0°, and the angle formed between the optical axis of the laser beam after being reflected by the reflective optical path component 3 and the normal of the speckle reducing element 2 is also 0°.

[0057] In other examples, the angle formed between the optical axis of the laser beam when it first passes through the speckle-eliminating element 2 and the normal to the speckle-eliminating element 2 can deviate from a certain angle, such as 5°, 10°, 15°, or 30°. Furthermore, the angle formed between the optical axis of the laser beam emitted after reflection from the reflective optical path component 3 and the surface of the speckle-eliminating element 2 can deviate from a certain angle, such as 5°, 10°, 15°, or 30°. As shown in FIG2 , the angle θ formed between the optical axis of the laser beam when it first passes through the speckle-eliminating element 2 and the normal to the speckle-eliminating element 2 is 15°. The angle formed between the optical axis of the laser beam when it exits the reflective optical path component 3 and the normal to the speckle-eliminating element 2 is also 15°. Compared to the speckle-eliminating optical path structure shown in FIG1 , the speckle-eliminating optical path structure in this example is shortened in the direction normal to the speckle-eliminating element 2.

[0058] It is understandable that within the range of 0° to 30° between the angle formed by the optical axis of the laser beam and the normal of the speckle-eliminating element 2, as the angle changes, the optical axis of the incident laser beam may not be perpendicular to the surface of the speckle-eliminating element 2, and the optical axis of the outgoing laser beam may not be perpendicular to the surface of the speckle-eliminating element 2. The incident laser beam and the outgoing laser beam passing through the speckle-eliminating element 2 may also be asymmetric, depending on the specific application scenario, and will not be further elaborated.

[0059] In some embodiments, the angle formed between the normal of the first reflective surface 31 and the surface of the speckle-eliminating element 2 is within a range of 45°±15°, and the angle formed between the normal of the second reflective surface 32 and the surface of the speckle-eliminating element 2 is within a range of 45°±15°. This angle setting between the first and second reflective surfaces 31 and 32 maintains substantial symmetry between the incident and outgoing laser beams, minimizing the length of the projection optical path and resulting in a compact overall structure, which facilitates a reduction in the size of the laser projection device. Setting the angles of the first and second reflective surfaces 31 and 32 within this range ensures that the angle formed between the optical axis of the laser beam and the normal of the speckle-eliminating element 2 is within a range of 0 to 30°, thereby improving the optical efficiency of the speckle-eliminating optical path structure. In some embodiments, at least one of the first and second reflective surfaces 31 and 32 is a flat or curved surface, and the curved surface is concave. In some embodiments, the concave surface is a spherical surface, an even-order aspheric surface, or a free-form surface. The even-order aspheric surface can be a hyperbolic surface, a paraboloid, or an ellipsoid.

[0060] As shown in Figure 1 , both the first and second reflective surfaces 31 and 32 are planar surfaces with their normals perpendicular to each other. The angles between the first and second reflective surfaces 31 and 32 and the surface of the speckle-reducing element 2 are both 45°. As shown in Figure 3 , both the first and second reflective surfaces 31 and 32 are curved surfaces with their normals perpendicular to each other. The angles between the normals of the first and second reflective surfaces 31 and 32 and the normal of the speckle-reducing element 2 are both 45°. As shown in Figure 5 , either the first or second reflective surface 31 and 32 can be planar, while the other can be curved, with their normals perpendicular to each other.

[0061] In some embodiments, the first and second reflective surfaces 31 and 32 are further provided with a reflective film 33. The reflective film 33 may be a dielectric reflective film or a metallic reflective film. In one example, the reflective film 33 is made of titanium dioxide (TiO2) and is applied to the first and second reflective surfaces 31 and 32 by spraying or coating, thereby increasing the reflectivity of the first and second reflective surfaces 31 and 32. In some embodiments, if the first and second reflective surfaces 31 and 32 are sufficiently smooth, the reflective film 33 may not be required, and the reflectivity of the first and second reflective surfaces 31 and 32 may be increased by total internal reflection.

[0062] In some embodiments, the reflective optical path assembly 3 includes a first reflector 3a and a second reflector 3b arranged at a preset angle, wherein the first reflector 3a is provided with a first reflective surface 31, and the second reflector 3b is provided with a second reflective surface 32. In some embodiments, at least one of the first reflector 3a and the second reflector 3b is a plane mirror or a curved mirror, and the preset angle between the first reflector 3a and the second reflector 3b can be in the range of 45°±15°.

[0063] In some embodiments, the reflective optical path component 3 includes a prism, which includes a first reflective surface 31 and a second reflective surface 32 set at a preset angle, and a transmissive surface 34 connecting the first reflective surface 31 and the second reflective surface 32, and the transmissive surface 34 is set toward the speckle-eliminating element 2.

[0064] As shown in Figure 4, the reflective optical path assembly 3 includes a triangular prism. The laser beam, after passing through the speckle reduction element 2 for the first time, is first transmitted through the transmission surface 34 before being incident on the first reflective surface 31. It is then reflected from the first reflective surface 31 to the second reflective surface 32. It is then reflected from the second reflective surface 32 and again transmitted through the transmission surface 34 before exiting. In some embodiments, the preset angle between the first reflective surface 31 and the second reflective surface 32 can be within a range of 45°±15°. It is understood that the two perpendicular sides of the triangular prism can also be coated with plane mirrors, with the two plane mirrors serving as the first reflective surface 31 and the second reflective surface 32, respectively.

[0065] In some embodiments, the speckle reduction optical path structure includes a driving mechanism 22 , the speckle reduction element 2 is a diffusion wheel, and a power output end of the driving mechanism 22 is coaxially arranged with the diffusion wheel to drive the diffusion wheel to rotate.

[0066] As shown in Figures 1 to 5 , speckle reduction element 2 is a diffuser wheel with a rough surface. Drive mechanism 22 can be a motor, coaxially arranged with the diffuser wheel to rotate the diffuser wheel about its center (indicated by the Z-axis in the figures), thereby improving the laser beam's speckle reduction effect. Furthermore, since the area where the diffuser wheel and motor overlap cannot transmit the laser beam, placing the motor on the side of the diffuser wheel facing laser light source 1 prevents the motor from blocking the laser beam's projection path, thereby increasing the utilization of speckle reduction element 2.

[0067] In some embodiments, the diffuser wheel is a disk structure with a diameter d ranging from 20 mm to 60 mm. In some embodiments, the minimum distance between the speckle-eliminating element 2 and the reflective optical path component 3 is 0.1d to 2d. As shown in Figure 4, the reflective optical path component 3 is a prism, and the distance between the speckle-eliminating element 2 and the transmissive surface 34 of the prism is 0.1d to 2d. In one example, the distance between the speckle-eliminating element 2 and the transmissive surface 34 of the prism is 0.42d. This configuration can further shorten the overall length of the projection optical path while ensuring optical efficiency, reducing the overall space occupied by the speckle-eliminating optical path structure, and thus reducing the volume of the laser projection device.

[0068] As shown in Figures 1 to 5, there is only one diffusion wheel. The drive mechanism 22 is located on the side of the diffusion wheel facing the laser light source 1 and is coaxial with the diffusion wheel. The area where the diffusion wheel and the drive mechanism 22 overlap cannot transmit the laser beam, and the transmission area of ​​the diffusion wheel is annular. When the drive mechanism 22 drives the diffusion wheel to rotate, the laser beam that passes through the diffusion wheel for the first time is located on one side of the rotation axis of the drive mechanism 22, and the laser beam that passes through the diffusion wheel for the second time is located on the other side of the rotation axis of the drive mechanism 22. For example, the position of the laser beam after passing through the diffusion wheel twice forms an angle of 180 degrees with the line connecting the rotation axis (a smaller angle is also possible; at 180 degrees, the required diameter of the diffusion wheel is minimized, which helps reduce the volume of the speckle reduction optical path). This improves the utilization of the speckle reduction element 2. Since a single speckle reduction element 2 can achieve two-fold speckle reduction of the laser beam, the speckle reduction effect can be effectively improved while reducing the overall volume of the speckle reduction optical path structure and reducing costs.

[0069] When the optical axis of the laser beam enters the diffusion wheel at an inclined angle, for example, when the angle formed by the optical axis of the laser beam and the normal of the diffusion wheel is 30°, the laser beam emitted from the diffusion wheel after being reflected by the reflective optical path component 3 may reach the area where the diffusion wheel and the drive mechanism 22 overlap and cannot be transmitted by the laser beam. The diameter of the diffusion wheel needs to be set to be large enough, but this may reduce the utilization rate of the diffusion wheel and increase the production cost.

[0070] To this end, as shown in Figure 6, two diffusion wheels are coplanar and spaced apart. One diffusion wheel, located on one side of the drive mechanism's rotating shaft, transmits the laser beam for the first time, while the other diffusion wheel, located on the other side of the drive mechanism's rotating shaft, transmits the laser beam for the second time. This allows the diameter of the diffusion wheels to be relatively small, reducing their manufacturing costs while also not increasing the overall length of the projection optical path, thus reducing the space occupied by the speckle reduction optical path structure.

[0071] In some embodiments, a half-wave plate 23 is further provided on the side of the speckle reduction element 2 facing the laser light source 1. As shown in FIG5 , the half-wave plate 23 is a birefringent crystal of a certain thickness. When normally incident light passes through it, the phase difference between the ordinary wave (O light) and the extraordinary wave (E light) is equal to π or an odd multiple of π. Such a crystal is called a half-wave plate, or simply a half-wave plate. When the O light propagates through the crystal, its refractive index remains constant regardless of the incident direction, exhibiting an isotropic property. The vibration direction of the E light is perpendicular to that of the O light, resulting in different refractive indices when propagating in different directions. The optical axis of the half-wave plate 23 is fixed in a fixed direction. When the half-wave plate 23 is integrated with the diffuser wheel, it rotates as the diffuser wheel rotates. Therefore, the polarization direction of the laser light after passing through the half-wave plate 23 is constantly changing, thereby further improving the speckle reduction effect.

[0072] In some embodiments, the speckle reduction optical path structure includes a driving mechanism 22 , the speckle reduction element 2 is a vibrating diffuser, and the driving mechanism 22 drives the vibrating diffuser to vibrate in any one of the XY plane, the YZ plane, and the XZ plane.

[0073] As shown in FIG7 , the driving mechanism 22 is a vibration controller, and the vibrating diffuser is a square diffuser. The driving mechanism 22 drives the vibrating diffuser to vibrate in any plane among the XY plane, YZ plane, and XZ plane according to a preset trajectory, which can effectively improve the despeckle effect of the laser beam.

[0074] In some embodiments, the shape of the vibrating diffuser is rectangular, and the diagonal dimension L thereof ranges from 20 mm to 60 mm. In some embodiments, the minimum distance between the vibrating diffuser and the reflective light path component is 0.1L to 2L. When the reflective light path component 3 is a prism, the distance between the vibrating diffuser and the transmissive surface 34 of the prism is 0.1L to 2L. In one example, the distance between the vibrating diffuser and the transmissive surface 34 of the prism is 0.42L. With such an arrangement, the overall length of the projection light path can be further shortened while ensuring the light effect, the overall occupied space of the speckle elimination light path structure can be reduced, and the volume of the laser projection device can be reduced.

[0075] In addition, the embodiment of the present disclosure also provides a speckle elimination optical path structure, which is similar to the structure shown in Figures 1 to 7, and can suppress the speckle of the laser beam twice. The difference is that the reflective optical path component 3 has only one reflective surface.

[0076] In some embodiments, as shown in Figure 8 , the speckle-eliminating element 2 is a diffuser wheel, the drive mechanism 22 is a motor, and the reflective optical path assembly 3 is disposed on the side of the speckle-eliminating element 2 away from the laser light source 1. The reflective optical path assembly 3 includes a reflective surface 30. After passing through the speckle-eliminating element 2 for the first time, the laser beam is incident on the reflective surface 30, reflected by the reflective surface 30, and then passes through the speckle-eliminating element 2 for the second time before exiting the speckle-eliminating element 2. The reflective surface 30 can be a flat surface, and a lens can be positioned before the reflective surface 30 to converge the light. The reflective surface 30 can also be a curved surface, preferably a concave surface. In some embodiments, the concave surface can be any of a spherical surface, an even-order aspheric surface, or a free-form surface. The even-order aspheric surface can be any of a hyperboloid, a paraboloid, or an ellipsoid.

[0077] When the distance between the reflective surface 30 and the speckle-anti-scattering element 2 meets a preset condition, the reflective surface 30 can ensure that the angle between the optical axis of the outgoing light beam, which has passed through the speckle-anti-scattering element 2 again, and the surface of the speckle-anti-scattering element 2 is in the range of 60° to 90°. Specifically, the larger the size of the speckle-anti-scattering element 2, the larger the distance. This distance is not specifically limited in this disclosure, and those skilled in the art can adapt it to the size of the speckle-anti-scattering element 2. It is understood that the speckle-anti-scattering element 2 can also be a vibrating diffuser, and the drive mechanism 22 is a vibration controller.

[0078] In addition, the embodiment of the present disclosure also provides a speckle elimination optical path structure, which is similar to the structure shown in Figures 1 to 7. The reflective optical path component 3 includes a first reflective surface 31 and a second reflective surface 32. The difference is that the position of the speckle elimination element 2 and the reflective optical path component 3 are different, and the speckle of the laser beam can be suppressed more times.

[0079] The speckle-eliminating element 2 is a vibrating diffuser, and the drive mechanism 22 is a vibration controller. The reflective optical path assembly 3 includes a first reflective surface 31 and a second reflective surface 32, which are arranged opposite and spaced apart on either side of the speckle-eliminating element 2. The laser beam emitted by the laser light source 1 passes through the speckle-eliminating element 2 for the first time and is incident on the first reflective surface 31. After being reflected by the first reflective surface 31, it passes through the speckle-eliminating element 2 for the second time and is incident on the second reflective surface 32. After being reflected by the second reflective surface 32, it passes through the speckle-eliminating element 2 for the third time and is emitted. This achieves a triple reduction in laser speckle reduction, significantly improving the laser's speckle reduction effect. Furthermore, the light that passes through the speckle-eliminating element 2 for the first time and the light that ultimately exits the speckle-eliminating element 2 are located on different sides of the element, resulting in the subsequent optical path structure overlapping with the overall length of the speckle-eliminating optical path. It is understood that the speckle-eliminating element 2 could also be a diffuser wheel, and the drive mechanism 22 could also be a motor.

[0080] In some embodiments, the number of the first reflective surface 31 and the number of the second reflective surface 32 can be multiple, and the multiple first reflective surfaces 31 and the multiple second reflective surfaces 32 are arranged on both sides of the speckle reducing element 2, and the two first reflective surfaces 31 and the two second reflective surfaces 32 are arranged on both sides of the speckle reducing element 2. In this way, the laser beam emitted by the laser light source 1 can pass through the speckle reducing element 2 four times, and the speckle of the laser beam is suppressed four times, thereby further improving the speckle reducing effect of the laser. The speckle-eliminating element 2 may be two coplanar and spaced apart elements 2, or three or more speckle-eliminating elements 2 may be provided as needed. In the present disclosure, since the plurality of first reflecting surfaces 31 and the plurality of second reflecting surfaces 32 are provided on both sides of the speckle-eliminating element 2, the same speckle-eliminating element 2 may be provided with a corresponding set of first reflecting surfaces 31 and second reflecting surfaces 32. This allows the same speckle-eliminating element 2 to suppress the speckle of the laser beam twice using the first reflecting surfaces 31 and the second reflecting surfaces 32. Two or more speckle-eliminating elements 2 may suppress the speckle of the laser beam three or more times, for example, four times, five times, or six times, before the laser beam enters the subsequent optical path.

[0081] As shown in FIG9 , the embodiment of the present disclosure further provides a laser projection device, including: the aforementioned speckle elimination optical path structure, a first lens assembly 8 , an image display device 9 and a lens 10 .

[0082] The first lens assembly 8 is positioned between the reflective optical path assembly 3 of the speckle-eliminating optical path structure and the image display device 9. It is used to converge the laser beam from the speckle-eliminating optical path structure onto the image display device 9, forming an illumination spot. The first lens assembly 8 includes at least one convex lens for converging a parallel beam of light onto the image display device 9. The image display device 9 can be a digital micromirror array (DMD), a reflective liquid crystal on silicon (LCOS), or a transmissive liquid crystal display (LCD). The size of the illumination spot matches the dimensions of the image display device 9, for example, both are rectangular. The lens 10 is used to project the image information emitted from the image display device 9 onto a screen.

[0083] In some embodiments, the speckle-eliminating optical path structure shown in Figures 1 to 7 is applied to a laser projection device. A reflective optical path assembly 3 is disposed on a side of the speckle-eliminating element 2 away from the laser light source 1 and includes a first reflective surface 31 and a second reflective surface 32 disposed at predetermined angles. The laser projection device also includes a second lens assembly 5 and a third lens assembly 6.

[0084] The second lens assembly 5 is arranged between the laser light source 1 and the speckle reducing element 2 of the speckle reducing optical path structure, and is used to focus the laser beam on the speckle reducing element 2. The second lens assembly 5 includes at least one lens, which is a convex lens for converging light.

[0085] The third lens assembly 6 is disposed between the speckle-combining element 2 and the reflective optical path assembly 3. It diverges the laser beam focused on the speckle-combining element 2 and directs it toward the first reflective surface 31 of the reflective optical path assembly 3. The laser beam from the first reflective surface 31 then exits through the second reflective surface 32 and reenters the third lens assembly 6. After convergence, the laser beam reenters the speckle-combining element 2. The third lens assembly 6 comprises one or two lenses. Two portions of a lens, or two linearly aligned lenses, correspond to the laser beam entering the first reflective surface 31 and exiting the second reflective surface 32, respectively. One portion of the lens or the other lens directs the converged beam from the speckle-combining element 2 toward the first reflective surface 31, while the other portion of the lens or the other lens directs the parallel incident light toward the speckle-combining element 2. Consequently, both the incident and exiting laser beams are focused on the transmission area of ​​the speckle-combining element 2, minimizing the increase in system etendue. This reduces the volume of the projection optical path and improves the optical efficiency and contrast of the laser projection device.

[0086] In some embodiments, the laser projection device further includes: a light homogenization component 7 .

[0087] The light homogenizing component 7 is disposed between the reflective optical path component 3 and the first lens component 8 , and is used to homogenize and shape the laser beam emitted from the speckle reduction element 2 .

[0088] In some embodiments, the light homogenizing assembly 7 includes a fly-eye lens 71 and a fourth lens assembly 72 . The fourth lens assembly 72 is disposed between the speckle reducing element 2 and the fly-eye lens 71 and is used to collimate the light emitted from the speckle reducing element 2 .

[0089] As shown in Figure 10, the fourth lens assembly 72 includes at least one lens, which is a convex lens for parallelizing the converged light after homogenization. The function of the fly-eye lens 71 is to spatially convolve the laser beam to make the laser beam irradiated on the image display device 9 more uniform.

[0090] Specifically, the fly-eye lens 71 is formed by a combination of a series of small lenses. To achieve uniform illumination, two rows of fly-eye lens arrays need to be arranged in parallel. The focus of each small unit lens in the first row of the fly-eye lens array coincides with the center of the corresponding small unit lens in the second row of the fly-eye lens array. The optical axes of the two rows of fly-eye lenses are parallel to each other. A condenser is placed behind the second row of fly-eye lenses, and the focal plane of the condenser is placed on the illumination screen to form a uniform illumination system. This allows the double-row fly-eye lens array to achieve high light energy utilization and uniform illumination over a large area, and has broad application prospects in the field of projection display.

[0091] The optical path principle of the fly-eye lens 71 is as follows: a light beam parallel to the optical axis passes through the first lens and is focused at the center of the second lens. The first row of fly-eye lenses and the light source form multiple light sources for illumination. Each lenslet in the second row of fly-eye lenses forms overlapping images of the multiple lenslets in the first row of fly-eye lenses onto the illumination surface. Because the first row of fly-eye lenses divides the entire broad light beam from the light source into multiple fine beams for illumination, any vertical nonuniformity within each fine beam is compensated for by the superposition of symmetrically positioned fine beams, effectively and evenly utilizing the light energy across the entire aperture. The light spot emitted from the second row of fly-eye lenses is focused onto the illumination screen by a condenser. This ensures that every point on the screen is illuminated by light from all points on the light source. Simultaneously, the light beams from every point on the light source converge and overlap within the same field of view on the illumination spot, resulting in a uniform square light spot.

[0092] In some embodiments, the light homogenizing component 7 is a quadrilateral cylinder with a rectangular or trapezoidal cross-section. As shown in FIG11 , the light homogenizing component 7 is a square rod 73 , which can be made of glass and can be a hollow quadrilateral cylinder or a solid quadrilateral cylinder.

[0093] In some embodiments, laser light source 1 includes a red laser R, a green laser G, and a blue laser B. The laser projection device further includes a light combining assembly 4, which is disposed between laser light source 1 and speckle reduction element 2 and is configured to combine the laser beams emitted by laser light source 1 into a single beam of light. The red laser R, green laser G, and blue laser B respectively emit red, green, and blue laser beams, which are combined into a single beam of white laser light by light combining assembly 4.

[0094] It is understood that when the speckle-eliminating optical path structure shown in FIG8 is applied to a laser projection device, the reflective optical path component 3 is disposed on the side of the speckle-eliminating element 2 away from the laser light source 1 and includes only one reflective surface 30. The laser projection device may also include the second lens assembly 5, the third lens assembly 6, the light homogenizing component 7, and the light combining component 4 described above. Specifically, when the reflective surface 30 is a plane, the third lens assembly 6 is used to converge light onto the reflective surface. When the reflective surface 30 is a curved surface, the third lens assembly 6 can be omitted and will not be described in detail. After the laser beam passes through the reflective surface 30 of the reflective optical path component 3 and the speckle-eliminating element 2 to suppress speckle twice, it is focused on the light homogenizing component 7. The light homogenizing component 7 then shapes the light and irradiates the image display device 9 to form an illumination spot. The image information emitted from the image display device 9 is projected onto the screen through the lens 10.

[0095] When the reflective optical path assembly 3 includes first and second reflective surfaces 31 and 32 that are spaced apart and opposed to each other, the speckle-eliminating element 2 is disposed between first and second reflective surfaces 31 and 32. The laser projection device may also include the aforementioned second lens assembly 5, light homogenization assembly 7, and light combining assembly 4. The second lens assembly 5 may be a combination of a convex lens and a concave lens, configured to direct the converged light rays parallel to the first reflective surface 31. Details thereof will not be repeated. After the laser beam undergoes multiple speckle suppression processes through the reflective optical path assembly 3 and the speckle-eliminating element 2, it is focused by the light homogenization assembly 7. The light homogenization and shaping by the light homogenization assembly 7 is then directed to the image display device 9, forming an illumination spot. The image information emitted from the image display device 9 is then projected onto the screen through the lens 10.

[0096] The laser projection device provided in the embodiments of the present disclosure adopts the speckle elimination optical path structure as described above, which can not only suppress the speckle of the laser beam at least twice, effectively improving the speckle elimination effect, but also shorten the overall length of the projection optical path, so that the volume of the laser projection device is reduced to the size of a can. It has a compact structure, light weight, strong mobility, is easy to carry, and is widely used in travel and business.

[0097] It should be noted that references in this specification to "one embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not necessarily every embodiment includes that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not.

[0098] It should be readily understood that “on,” “above,” and “over” in this disclosure should be interpreted in the broadest manner, such that “on” means not only “directly on something,” but also includes “on something” with intervening features or layers therebetween, and “above” or “over” includes not only the meaning of “above” or “over,” but also includes “above” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0099] Additionally, spatially relative terms, such as "below," "beneath," "beneath," "above," and the like, may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be in other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0100] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. Speckle elimination optical path structure, including: a laser light source configured to emit a laser beam; a speckle reduction element configured to transmit the laser beam emitted by the laser light source; as well as A reflective optical path component includes a reflective surface, wherein: The laser beam emitted by the laser light source enters the speckle reduction element and reaches the reflective surface, and is reflected by the reflective surface and enters the speckle reduction element. The laser beam emitted by the laser light source passes through the speckle reduction element at least twice in the process of changing direction through the reflective surface of the reflective optical path component, so as to suppress the speckle of the laser beam at least twice, and then is emitted from the speckle reduction element, wherein: The optical axis of the laser beam emitted from the speckle reducing element is emitted at an angle of 60° to 90° with the surface of the speckle reducing element, and then enters the subsequent optical path.

2. The speckle-eliminating optical path structure according to claim 1, wherein: The reflective light path component is arranged on a side of the speckle elimination element away from the laser light source, and includes a first reflective surface and a second reflective surface arranged at a preset angle; The laser beam emitted by the laser light source passes through the speckle reducing element for the first time and is incident on the first reflecting surface, is reflected by the first reflecting surface to the second reflecting surface, and then passes through the speckle reducing element for the second time and is emitted.

3. The speckle-eliminating optical path structure according to claim 1 or 2, wherein: The angle between the optical axis of the laser beam passing through the speckle reducing element for the first time and the surface of the speckle reducing element is in the range of 60° to 90°.

4. The speckle-eliminating optical path structure according to claim 2, wherein: The angle formed by the normal of the first reflecting surface and the surface of the speckle reducing element is in the range of 45°±15°; and The angle formed by the normal of the second reflecting surface and the surface of the speckle-eliminating element is in the range of 45°±15°.

5. The speckle-eliminating optical path structure according to claim 2 or 4, wherein: At least one of the first reflecting surface and the second reflecting surface is a flat surface or a curved surface, and the curved surface is a concave surface.

6. The speckle-eliminating optical path structure according to claim 5, wherein: The concave surface is any one of a spherical surface, an even-order aspherical surface or a free-form surface.

7. The speckle-eliminating optical path structure according to any one of claims 2, 4 to 6, wherein: The first reflecting surface and the second reflecting surface are respectively provided with a reflecting film.

8. The speckle-eliminating optical path structure according to any one of claims 2, 4 to 7, wherein: The reflective optical path component includes a first reflector and a second reflector arranged at a preset angle, the first reflector is provided with the first reflective surface, and the second reflector is provided with the second reflective surface.

9. The speckle-eliminating optical path structure according to any one of claims 2, 4 to 8, wherein: The reflective optical path component includes a prism, which includes the first reflective surface, the second reflective surface, and a transmissive surface connecting the first reflective surface and the second reflective surface, and the transmissive surface is arranged toward the speckle-eliminating element.

10. The speckle-eliminating optical path structure according to any one of claims 1 to 9, further comprising a driving mechanism, wherein the speckle-eliminating element is a diffusion wheel, a power output end of the driving mechanism is coaxially arranged with the diffusion wheel to drive the diffusion wheel to rotate, and the diameter of the diffusion wheel is d.

11. The speckle-eliminating optical path structure according to claim 10, wherein: The diffusion wheel is a disc structure, and its diameter d ranges from 20 mm to 60 mm.

12. The speckle-eliminating optical path structure according to claim 10 or 11, wherein: The minimum distance between the diffusion wheel and the reflective light path component is 0.1d to 2d.

13. The speckle-eliminating optical path structure according to any one of claims 10 to 12, wherein: A half-wave plate is further provided on the side of the speckle reducing element facing the laser light source. The half-wave plate and the speckle reducing element are coaxially arranged and connected as a whole.

14. The speckle-eliminating optical path structure according to any one of claims 1 to 13, further comprising a driving mechanism, wherein the speckle-eliminating element is a vibrating diffuser, and the driving mechanism drives the vibrating diffuser to vibrate in any one of an XY plane, a YZ plane, and an XZ plane.

15. The speckle-eliminating optical path structure according to claim 14, wherein: The vibration diffuser is rectangular in shape, and its diagonal dimension L ranges from 20 mm to 60 mm.

16. The speckle-eliminating optical path structure according to claim 15, wherein: The minimum distance between the vibration diffuser and the reflective light path component is 0.1L to 2L.

17. Laser projection equipment, including: The speckle-eliminating optical path structure according to any one of claims 1 to 16; an image display device and a first lens assembly, wherein the first lens assembly is disposed between the speckle-eliminating optical path structure and the image display device and is configured to converge the laser beam from the speckle-eliminating optical path structure onto the image display device to form an illumination spot; as well as The lens is configured to project the image information emitted from the image display device onto a screen.

18. The laser projection device according to claim 17, wherein: The reflective light path component is arranged on a side of the speckle elimination element away from the laser light source, and includes a first reflective surface and a second reflective surface arranged at a preset angle; The laser projection device further comprises: a second lens assembly, disposed between the laser light source of the speckle-eliminating optical path structure and the speckle-eliminating element, and configured to focus the laser beam onto the speckle-eliminating element; a third lens assembly disposed between the speckle reducing element and the reflective optical path assembly, and configured to diverge the laser beam focused on the speckle reducing element and make it incident on the first reflective surface of the reflective optical path assembly; the laser beam from the first reflective surface is emitted through the second reflective surface and re-enters the third lens assembly; and after being converged, re-enters the speckle reducing element; The light homogenizing component is disposed between the reflective optical path component and the first lens component, and is configured to perform light homogenization and shaping on the laser beam emitted from the speckle eliminating element.

19. The laser projection device according to claim 18, wherein: The light homogenizing assembly includes a fly-eye lens and a fourth lens assembly. The fourth lens assembly is disposed between the speckle reducing element and the fly-eye lens and is configured to collimate the laser beam emitted from the speckle reducing element.

20. The laser projection device according to claim 18 or 19, wherein: The light homogenizing component is a quadrilateral column, and its cross-section is rectangular or trapezoidal.

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