A laser speckle-eliminating illumination system

Abstract

The utility model belongs to laser projection display technical field, concretely relates to a kind of laser speckle illumination system, comprising: laser light source, wavelength plate, compression shaping lens, first reflector, speckle device, collimating lens group, second reflector are sequentially arranged in first direction, and first reflector, light path shaping lens, homogenization device are sequentially arranged in second direction;First reflector center is provided with hole;First reflector upper surface is covered with reflecting film, and reflecting film is arranged in the side close to speckle device;Laser light source emits laser beam, polarization state is modulated by wavelength plate and compression shaping lens is compressed and shaped, enter speckle device by the hole of first reflector and carry out first speckle, after collimating by collimating lens group, it is incident to second reflector, after reflecting by second reflector, after collimating by collimating lens group, it enters speckle device and carries out second speckle, after reflecting by first reflector, it enters homogenization device after adjusting by light path shaping lens.

Description

Technical Field

[0001] This utility model belongs to the field of laser projection display technology, specifically relating to a laser spot-reducing illumination system. Background Technology

[0002] Laser projection technology, with its significant advantages such as high brightness, high contrast, wide color gamut, and strong color performance, has seen its market share in the projection display market continue to rise, and sales of related products have also been increasing year by year. However, lasers have the inherent characteristic of high coherence. When a laser beam is projected onto a rough surface (such as white paper, a wall, or a projection screen), the unevenness of the surface exceeds the laser wavelength, causing random interference of light. This results in a grainy texture on the projected image, known as speckle. The presence of speckle significantly reduces image quality, and prolonged viewing can cause eye fatigue, greatly diminishing the viewing experience. Therefore, reducing speckle has become a key technical problem that urgently needs to be solved in the field of laser projection.

[0003] Currently, to address the speckle suppression problem, single or combined strategies such as multi-wavelength light source mixing, projection screen dithering, laser speckle suppressors, and multimode fiber bundles are mainly employed. These methods can effectively reduce speckle effects, but they also have certain limitations in practical applications. Specifically, using a single speckle suppressor optical device generally yields only moderate speckle reduction results. While using multiple dynamic or static speckle suppressors, or a combination of dynamic and static methods, can effectively suppress speckle, the use of multiple speckle suppressors leads to higher costs, limiting large-scale application and widespread adoption. Dividing a dynamic speckle suppressor into upper and lower parts allows for multiple speckle suppression functions on the same structure, improving the speckle reduction effect. However, this structure often only suppresses speckle from a specific light source direction, and its large structural volume results in a large overall light source system size. Utility Model Content

[0004] This invention provides a laser speckle elimination illumination system. By using a speckle elimination device at the same location to eliminate speckle twice, the coherence of the laser can be eliminated twice, improving the speckle elimination effect. By designing a first reflector with a hole, the laser beam in the first direction can pass directly through, and the laser beam in the opposite direction of the first direction can be reflected to the second direction, which is beneficial to the miniaturization of the system structure. The second reflector realizes optical path multiplexing, and the reflection of the first reflector realizes optical path deflection, which can reduce the optical path volume and facilitate the light collection of the system. The whole system has the advantages of compact structure, small size and low cost.

[0005] A laser speckle elimination illumination system, comprising: The system comprises a laser source, a wavelength plate, a compression and shaping lens, a first reflecting mirror, a speckle-reducing device, a collimating lens group, a second reflecting mirror, an optical path shaping lens, and a beam homogenizing device. The laser source, wavelength plate, compression and shaping lens, first reflecting mirror, speckle-reducing device, collimating lens group, and second reflecting mirror are arranged coaxially along a first direction. The first reflecting mirror, optical path shaping lens, and beam homogenizing device are arranged coaxially along a second direction. A hole is formed in the center of the first reflecting mirror. The upper surface of the first reflecting mirror is covered with a reflective film, which is disposed on the side closest to the speckle-reducing device. The laser light source emits a laser beam, which is sequentially modulated by the wavelength plate and compressed and shaped by the compression and shaping lens. The beam then enters the speckle-reducing device through the hole of the first reflector for initial speckle reduction, is collimated by the collimating lens group, and then incident on the second reflector. After being reflected along the original optical path by the second reflector, it is collimated by the collimating lens group and enters the speckle-reducing device for secondary speckle reduction. Finally, it is reflected by the first reflector to the optical path shaping lens for optical path adjustment before entering the homogenizing device.

[0006] By performing two speckle reduction operations using a speckle reduction device at the same location, the coherence of the laser can be eliminated twice, improving the speckle reduction effect. Furthermore, by designing a first reflecting mirror with a hole, the laser beam in the first direction can pass directly through, while the laser beam in the opposite direction of the first direction can be reflected to the second direction, which is beneficial for the miniaturization of the system structure. By using the second reflecting mirror to achieve optical path multiplexing and the first reflecting mirror to achieve optical path reversal, the optical path volume can be reduced, which is beneficial for the system to collect light. As a result, the entire system has the advantages of compact structure, small size, and low cost.

[0007] Furthermore, the first reflector forms a 45° angle with the second direction, which is used to reflect the laser beam in the opposite direction of the first direction to the second direction.

[0008] By setting the angle of the first reflector, it is possible to achieve optical path reversal, reflecting the laser beam in the opposite direction of the first direction to the second direction, thereby achieving miniaturization of the system structure.

[0009] Furthermore, the speckle elimination device is connected to a driving component for driving the speckle elimination device to dynamically eliminate speckle; the speckle elimination device includes a laser speckle suppressor and a rotating wheel with a diffuser.

[0010] By driving the speckle removal device to move through the driving components, laser coherence can be eliminated, thus achieving dynamic speckle removal.

[0011] Furthermore, the optical path of the speckle-reducing device is multiplexed with that of the collimating lens group; the optical path of the collimating lens group is multiplexed with that of the second reflecting mirror.

[0012] Optical path multiplexing design enables system miniaturization and reduces system cost.

[0013] Furthermore, the laser source includes a single-wavelength laser source and an RGB multi-wavelength laser source, used to emit laser light.

[0014] Furthermore, the wavelength plate includes a half-wave plate and a quarter-wave plate, used to change the polarization state of the emitted laser source.

[0015] Furthermore, the compression shaping lens includes a concave surface and a convex surface, with the concave surface disposed on the side near the first reflector and the convex surface disposed on the side near the wavelength plate.

[0016] The concave and convex design of the compression shaping lens helps to effectively compress and shape the laser beam, thus facilitating the laser beam with a compressed aperture to pass through the hole of the first reflecting mirror and enter the speckle removal device for speckle removal.

[0017] Furthermore, the refractive index of the compression-shaping lens is in the range of 1.6 to 1.85.

[0018] Furthermore, the aperture shape of the first reflector includes square, circular, and elliptical shapes, for the laser beam to pass through in the first direction.

[0019] Furthermore, the homogenizing device includes a compound eye, a homogenizing rod, or a diffraction device, used to homogenize the laser beam.

[0020] By designing a light-uniforming device, it is possible to reduce the uneven illumination caused by the loss of intermediate light energy due to the hole in the first reflector.

[0021] The beneficial effects of this utility model are as follows: By performing two speckle reduction operations using a speckle reduction device at the same location, the coherence of the laser can be eliminated twice, improving the speckle reduction effect. Furthermore, by designing a first reflecting mirror with a hole, the laser beam in the first direction can pass directly through, while the laser beam in the opposite direction of the first direction can be reflected to the second direction, which is beneficial for the miniaturization of the system structure. By using the second reflecting mirror to achieve optical path multiplexing and the first reflecting mirror to achieve optical path reversal, the optical path volume can be reduced, which is beneficial for the system to collect light. As a result, the entire system has the advantages of compact structure, small size, and low cost. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 The optical path diagram for the compression shaping lens; Figure 3 This is a schematic diagram of the reflector.

[0023] Figure label: 1. Laser source; 2. Wavelength plate; 3. Compression shaping lens; 31. Convex surface; 32. Concave surface; 4. First reflecting mirror; 41. Hole; 5. Anti-spot device; 6. Collimating lens group; 7. Second reflecting mirror; 8. Optical path shaping lens; 9. Beam homogenizing device. Detailed Implementation

[0024] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0025] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0027] Figure 1The diagram illustrates a laser speckle reduction illumination system, comprising a laser source 1, a wavelength plate 2, a compression shaping lens 3, a first reflector 4, a speckle reduction device 5, a collimating lens group 6, and a second reflector 7 arranged coaxially in sequence along a first direction, and a first reflector 4, an optical path shaping lens 8, and a light homogenizing device 9 arranged coaxially in sequence along a second direction. By using the speckle reduction device 5 at the same location for two speckle reductions, the coherence of the laser can be eliminated twice, improving the speckle reduction effect. Furthermore, the design of the first reflector 4 with a hole 41 allows the laser beam in the first direction to pass directly through, while also reflecting the laser beam in the opposite direction to the second direction, thus utilizing the system's miniaturized design. The use of the second reflector 7 for optical path multiplexing and the reflection by the first reflector 4 for optical path reversal reduces the optical path volume, facilitating light collection and giving the entire system the advantages of compact structure, small size, and low cost.

[0028] Specifically, the laser source 1 includes a single-wavelength laser source 1 and an RGB multi-wavelength laser source 1, which are used to emit laser light.

[0029] Specifically, the wavelength plate 2, with its half-wave plate and quarter-wave plate, is used to change the polarization state of the emitting laser source 1, thereby causing some of the laser light to be converted into other polarization states. The mixed beam of multiple polarization states can reduce the effect of speckle reduction.

[0030] Specifically, such as Figure 2 As shown, the compression shaping lens 3 includes a concave surface 32 and a convex surface 31. The concave surface 32 is disposed on the side near the first reflector 4, and the convex surface 31 is disposed on the side near the wavelength plate 2. The design of the concave surface 32 and the convex surface 31 of the compression shaping lens 3 can help to effectively compress and shape the laser beam, thereby facilitating the laser beam with compressed laser beam aperture to pass through the hole 41 of the first reflector 4 and then enter the speckle elimination device 5 for speckle elimination.

[0031] In this embodiment, the refractive index of the compression shaping lens 3 is in the range of 1.6 to 1.85.

[0032] Specifically, the first reflector 4 is at a 45° angle to the second direction, and the surface of the side closest to the speckle-reducing device 5 is covered with a reflective film to reflect the laser beam in the opposite direction of the first direction to the second direction, thereby realizing the optical path reversal and facilitating the miniaturization of the system structure; the first reflector 4 has a hole 41 in the center so that the laser beam in the first direction can pass through directly.

[0033] In this embodiment, as Figure 3 As shown, the hole 41 of the first reflector 4 is square in shape.

[0034] Specifically, the speckle elimination device 5 includes a laser speckle suppressor (LSR) and a rotating wheel with a diffuser. The speckle elimination device 5 is connected to a driving component, which drives the speckle elimination device 5 to eliminate laser coherence, thereby achieving dynamic speckle elimination.

[0035] It should be noted that in practical applications, the diffusion angle of the diffuser used in the rotating wheel with diffuser is in the range of 3° to 8°, so as to avoid the diffusion effect being weakened by the diffusion angle being too small and the system structure volume being increased by the diffusion angle being too large.

[0036] Specifically, the collimating lens group 6 is used to shape the laser beam that has been speckled by the speckle-reducing device 5 into parallel light and incident it onto the second reflecting mirror 7, and to reshape the laser beam reflected by the second reflecting mirror 7 before incidenting it onto the speckle-reducing device 5.

[0037] Specifically, the second reflector 7 is used to reflect the laser beam collimated by the collimating lens group 6 along the original optical path, so as to realize optical path multiplexing.

[0038] Specifically, the optical path shaping lens 8 is used to shape the laser beam reflected by the first reflecting mirror 4, thereby avoiding excessive side lobes or diffraction light from the system and thus improving the light efficiency.

[0039] In this embodiment, the laser beam angle shaped by the optical path shaping lens 8 is less than 5°.

[0040] Specifically, the light homogenizing device 9 includes a compound eye, a light homogenizing rod, or a diffraction device, which is used to homogenize the laser beam, thereby reducing the illumination non-uniformity caused by the intermediate light energy loss due to the hole 41 of the first reflector 4, so that the laser beam is focused into uniform light on the projection display chip (DMD, LCOS, LCD), thereby improving the illumination uniformity.

[0041] In this embodiment, the speckle-reducing device 5 is driven to move by a driving component. Furthermore, the optical paths of the speckle-reducing device 5 and the collimating lens group 6 are multiplexed; the optical paths of the collimating lens group 6 and the second reflecting mirror 7 are also multiplexed. Through the optical path multiplexing design, the system structure can be miniaturized, while reducing the system cost.

[0042] The working principle of this embodiment is as follows: Laser source 1 emits a laser beam, which is successively modulated by wavelength plate 2, compressed and shaped by compression and shaping lens 3, and enters speckle elimination device 5 through hole 41 of first reflector 4. Under the action of driving component, it undergoes speckle elimination once, and is then collimated by collimating lens group 6 before entering second reflector 7. It is reflected by second reflector 7 along the original optical path, collimated a second time by collimating lens group 6, and then enters speckle elimination device 5 for secondary speckle elimination. Finally, it is reflected by first reflector 4 to optical path shaping lens for optical path adjustment before entering light homogenizing device 9.

[0043] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A laser speckle elimination illumination system, characterized in that, include: The system comprises a laser source, a wavelength plate, a compression and shaping lens, a first reflecting mirror, a speckle-reducing device, a collimating lens group, a second reflecting mirror, an optical path shaping lens, and a beam homogenizing device. The laser source, wavelength plate, compression and shaping lens, first reflecting mirror, speckle-reducing device, collimating lens group, and second reflecting mirror are arranged coaxially along a first direction. The first reflecting mirror, optical path shaping lens, and beam homogenizing device are arranged coaxially along a second direction. A hole is formed in the center of the first reflecting mirror. The upper surface of the first reflecting mirror is covered with a reflective film, which is disposed on the side closest to the speckle-reducing device. The laser light source emits a laser beam, which is sequentially modulated by the wavelength plate and compressed and shaped by the compression and shaping lens. The beam then enters the speckle-reducing device through the hole of the first reflector for initial speckle reduction, is collimated by the collimating lens group, and then incident on the second reflector. After being reflected along the original optical path by the second reflector, it is collimated by the collimating lens group and enters the speckle-reducing device for secondary speckle reduction. Finally, it is reflected by the first reflector to the optical path shaping lens for optical path adjustment before entering the homogenizing device.

2. The laser speckle elimination illumination system according to claim 1, characterized in that: The first reflector is at a 45° angle to the second direction, and is used to reflect the laser beam in the opposite direction of the first direction to the second direction.

3. The laser speckle elimination illumination system according to claim 1, characterized in that: The speckle reduction device is connected to a driving component and is used to drive the speckle reduction device to dynamically reduce speckle; the speckle reduction device includes a laser speckle suppressor and a rotating wheel with a diffuser.

4. The laser speckle elimination illumination system according to claim 1, characterized in that: The optical path of the speckle-reducing device is multiplexed with that of the collimating lens group; the optical path of the collimating lens group is multiplexed with that of the second reflecting mirror.

5. The laser speckle elimination illumination system according to claim 1, characterized in that: The laser source includes a single-wavelength laser source and an RGB multi-wavelength laser source, used to emit laser light.

6. The laser speckle elimination illumination system according to claim 1, characterized in that: The wavelength plate includes a half-wave plate and a quarter-wave plate, which are used to change the polarization state of the emitted laser source.

7. The laser speckle elimination illumination system according to claim 1, characterized in that: The compression-shaping lens includes a concave surface and a convex surface, with the concave surface disposed on the side near the first reflector and the convex surface disposed on the side near the wavelength plate.

8. The laser speckle elimination illumination system according to claim 1, characterized in that: The refractive index range of the compression-shaping lens is 1.6 to 1.

85.

9. A laser speckle elimination illumination system according to claim 1, characterized in that: The aperture shape of the first reflector includes square, circular, and elliptical shapes, for a laser beam to pass through in the first direction.

10. A laser speckle elimination illumination system according to claim 1, characterized in that: The homogenizing device includes a compound eye, a homogenizing rod, or a diffraction device, used to homogenize the laser beam.

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