Laser projection device and laser projection system

Abstract

The application relates to a laser projection device and a laser projection system. A depolarizer component is additionally arranged on a laser display light path between a light source and a light modulation component, so that birefringence and interference effects occur in the depolarizer component, and polarized light is converted into random polarized light. Birefringence caused by lens stress in the light modulation component usually has a fixed fast and slow axis direction, which can affect the polarization state of light passing through the lens. In the embodiments provided by the application, the depolarizer component can rotate around the light beam propagation direction in the working state. When the light beam passes through the lens each time, the polarization direction of the light changes relative to the axis of the stress birefringence. The phase delay caused by the stress has different effects in different directions, and the effects are offset after time averaging, so that the negative influence of the birefringence effect caused by the lens stress on the depolarization effect of the depolarizer component can be reduced, and the speckle contrast can be greatly reduced, and the speckle suppression effect is improved.

Description

Technical Field

[0001] This application relates to the field of optoelectronic technology, and in particular to a laser projection device and a laser projection system. Background Technology

[0002] For laser projection products, the high coherence of laser light can easily cause speckle on the imaging side, reducing the quality of the projected image. Improving laser speckle is therefore crucial for enhancing the performance of laser projection products. Summary of the Invention

[0003] Therefore, it is necessary to provide a laser projection device and laser projection system that can effectively suppress speckle.

[0004] In a first aspect, a laser projection device is provided, comprising:

[0005] A light source used to provide a laser beam;

[0006] An optical modulation component is used to receive a laser beam provided by a light source and modulate the laser beam into an image beam, which is used for imaging.

[0007] The depolarizer assembly is located in the laser display optical path between the light source and the light output side of the light modulation assembly. The depolarizer assembly supports rotation about the beam propagation direction.

[0008] A lens is used to project an image beam emitted from a light modulation component onto a display substrate to display an image.

[0009] In one embodiment, when the optical modulation assembly includes a digital micromirror device, the depolarizer assembly rotates about the beam propagation direction as an axis within a range of -5° to 5°.

[0010] In one embodiment, the depolarizer assembly is rotated by an angle greater than 0 degrees and less than or equal to 90 degrees.

[0011] In one embodiment, the depolarizer assembly includes a depolarizer comprising two anisotropic crystals.

[0012] 5. The laser projection device according to claim 4, characterized in that both anisotropic crystals are wedge-shaped crystals, and the wedge angle of the wedge-shaped crystals is in the range of 0 degrees to 10 degrees; and / or, the difference in optical axis angle between the two wedge-shaped crystals is greater than 0 degrees and less than 90 degrees.

[0013] In one embodiment, where the depolarizer assembly supports reflection of the incident beam based on the incident surface, the laser projection device further includes:

[0014] The reflective film is attached to the side of the depolarizer assembly away from the incident light.

[0015] In one embodiment, the reflective film layer is a metal coating or a dielectric coating.

[0016] In one embodiment, the material of the metal coating includes at least one of aluminum, silver, and gold; and / or, the thickness of the metal coating ranges from 10 nm to 999 nm; and / or, the material of the dielectric coating includes a dielectric material; and / or, the thickness of the dielectric coating is one-quarter or one-half of the wavelength of the corresponding laser beam.

[0017] In one embodiment, the light source is used to provide red laser, green laser and blue laser; the depolarizer assembly is used to be disposed in the laser display optical path of at least one of the red laser and green laser beams.

[0018] In one embodiment, the light source includes:

[0019] Red laser, used to provide red laser light;

[0020] Green laser, used to provide green laser light;

[0021] Blue laser, used to provide blue laser light;

[0022] Multiple beam combiner groups are respectively positioned on the output side of the red laser, green laser and blue laser to mix and reflect the incident laser light;

[0023] The beam-contracting component is used to receive the laser reflected by the beam combiner group and to concentrate the incoming laser beam before shooting it out.

[0024] Among them, the input or output side of the target beam combining mirror group is provided with a depolarizer assembly, and the target beam combining mirror group is the beam combining mirror group corresponding to the red laser and / or the beam combining mirror group corresponding to the green laser.

[0025] In one embodiment, the target beam combining lens assembly includes a diffuser plate integrated with a polarizer assembly; or, the beam shrinking component includes a compound eye lens integrated with a polarizer assembly.

[0026] In one embodiment, the optical modulation component includes:

[0027] Multiple illumination lens groups, with a depolarizer assembly positioned in the optical path between two adjacent illumination lens groups.

[0028] In one embodiment, the depolarizer assembly includes:

[0029] The depolarizer is located in the laser display optical path between the light source and the light output side of the light modulation component;

[0030] Vibration device, used to drive the depolarizer to vibrate.

[0031] Secondly, a laser projection system is provided, including the aforementioned laser projection device and projection screen.

[0032] The aforementioned laser projection equipment and laser projection system have at least the following beneficial effects:

[0033] The laser beam provided by the light source is modulated into an image beam by an optical modulation component. By adding a depolarizer component to the laser display optical path between the light source and the output side of the optical modulation component, the polarized light undergoes birefringence and interference effects within the depolarizer component, thereby converting the polarized light into randomly polarized light. The birefringence caused by lens stress in the optical modulation component typically has a fixed fast and slow axis direction, which affects the polarization state of the light passing through the lens. However, the depolarization mechanism of the depolarizer component is fixed and cannot cope with this stress-induced polarization state change, thus affecting the depolarization effect. In the embodiments provided in this application, the depolarizer component supports rotation about the beam propagation direction during operation. During the rotation of the depolarizer component, the polarization direction of the light changes relative to the axis of stress birefringence each time the beam passes through the lens. The phase delay caused by stress produces different effects in different directions, which cancel each other out after time averaging. This reduces the negative impact of the birefringence effect of lens stress on the depolarization effect of the depolarizer component, thereby significantly reducing speckle contrast and improving speckle suppression. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of a laser projection device using conventional technology.

[0036] Figure 2 One of the structural schematic diagrams of a laser projection device according to one or more embodiments;

[0037] Figure 3 A partial structural schematic diagram of a laser projection device according to one or more embodiments;

[0038] Figure 4 This is a schematic diagram illustrating the polarization effect of a depolarizer assembly under different rotation angles in one or more embodiments.

[0039] Figure 5The diagram shows the structure of a dual-wedge depolarizer as one or more embodiments.

[0040] Figure 6 A second schematic diagram of the structure of a laser projection device according to one or more embodiments;

[0041] Figure 7 A third schematic diagram of the structure of a laser projection device according to one or more embodiments;

[0042] Figure 8 Fourth schematic diagram of a laser projection device according to one or more embodiments;

[0043] Figure 9 Fifth schematic diagram of a laser projection device according to one or more embodiments;

[0044] Figure 10 Sixth schematic diagram of the structure of a laser projection device according to one or more embodiments;

[0045] Figure 11 Seventh schematic diagram of the structure of a laser projection device according to one or more embodiments;

[0046] Figure 12 Eighth schematic diagram of a laser projection device according to one or more embodiments;

[0047] Figure 13 Schematic diagram nine of a laser projection device according to one or more embodiments;

[0048] Figure 14 This is a schematic diagram of the structure of a laser projection system according to one or more embodiments. Detailed Implementation

[0049] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0050] Unless otherwise defined, 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. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0051] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0052] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0053] In the process of combining red, green, and blue lasers through a dichroic filter and then incident on a light guide tube via a lens, the high coherence of the laser means that the emitted light waves have a fixed phase relationship in space, and the intensity distribution of the laser is Gaussian, implying that its energy distribution is not uniform. Therefore, when the laser beam shines on the surface of an object, coherent light waves from different locations will interfere. Because these coherent light waves have different optical path differences and other conditions, the light waves will reinforce each other at some locations in space, while canceling each other out at other locations. This results in a speckle pattern of alternating bright and dark areas, which severely affects the uniformity and visual quality of the final projected image, making the image appear unclear and uneven.

[0054] In traditional technologies, such as Figure 1 As shown, a diffuser 103 and a diffuser wheel 104 are added in front of the light guide 105. The surface of the diffuser 103 has a microscopic irregular structure, which causes scattering when the laser passes through, making the originally highly coherent laser beam provided by the light source 101 more disordered in space, thus destroying the coherence between light waves at different positions. The diffuser wheel 104 further enhances this disturbance effect on the laser beam by rotating or vibrating (rotating or vibrating diffuser), continuously changing the propagation state of the laser. This makes it difficult for the laser beam to form stable interference as it enters the light guide 105 and passes through the subsequent illumination system 106, thereby effectively suppressing speckle formation. As a result, when the beam is finally projected onto the projection screen through the digital micromirror device 107 (DMD) and lens 108, the projected image is more uniform and clearer, and the visual effect is significantly improved. It should be noted that when the optical axes of the light source 101 and the diffuser 103 are not aligned, a reflector 109 can be added to project the laser beam projected by the light source 101 onto the dichroic filter 102. After the light is combined by the dichroic filter 102, it is projected onto the diffuser 103.

[0055] However, the applicant discovered that while the diffuser and diffuser wheel change the direction of laser propagation and destroy coherence, they also cause significant and relatively irregular changes in optical path parameters such as the divergence angle of the laser beam. This necessitates a more complex optical system to readjust and optimize the optical path to ensure that the light is accurately directed onto subsequent optical components such as the light guide. This means that more space is needed to install these complex optical systems, which is inconsistent with the development trend of small-sized laser projection equipment.

[0056] Furthermore, the number and packaging method of semiconductor laser chips used in laser displays are positively correlated with the final output luminous flux. For small-sized laser projection devices, as the laser chips become smaller, the spot size and optical spread also decrease. Consequently, speckle becomes more prominent on relatively small projection screens. Even slight speckle can be noticeable on small screens, causing uneven brightness and graininess in certain areas, significantly impacting image clarity, detail, and overall visual effect. Traditional diffuser and diffuser wheel solutions primarily disrupt coherence through relatively random methods such as laser scattering, offering limited precision control and failing to meet the speckle suppression precision requirements of small-sized laser projection devices.

[0057] Based on this, in one exemplary technology, a laser projection device 1 is provided, such as... Figure 2 As shown, it includes: a light source 11, a light modulation assembly 12, a polarizer assembly 13, and a lens 14. Wherein:

[0058] Light source 11 is used to provide a laser beam. A single laser beam has high directionality and monochromaticity. Light source 11 may include a laser assembly that can provide a laser beam of at least one color. In some examples, the laser assembly can emit blue laser light, and the light source also includes a wavelength conversion device for receiving blue laser excitation to generate other primary colors besides blue, which together form the illumination beam. In some examples, light source 11 includes a tri-color laser assembly for emitting a tri-color laser beam, eliminating the need for a wavelength conversion device. The tri-color laser has a wide color gamut and high brightness, providing a high-quality illumination beam. For example, in business presentations such as business meetings and product launches, a tri-color laser beam can ensure accurate and vibrant colors in projected PPTs, videos, and other content. Even in brightly lit meeting room environments, its high brightness and excellent color performance clearly display key information, charts, and product details, allowing the audience to accurately understand the presentation content and enhancing the presentation effect. For example, in home theater settings, tri-color light sources can create a cinematic color atmosphere, faithfully reproducing the original color style of the film. Whether it's a classic film with a retro tone or a modern blockbuster with vibrant colors, the precise coordination of the tri-color laser light sources can perfectly present the film, providing family members with an immersive viewing experience, as if they were in a professional cinema. Furthermore, in teaching and training settings, tri-color laser light sources ensure clear display of teaching materials and video resources. Richly colored images and text can better attract students' attention, improving the fun of teaching and student learning outcomes. Moreover, there are no concerns about the lifespan of the light source even after long-term use, reducing maintenance costs.

[0059] The optical modulation component 12 is used to receive a laser beam provided by the light source 11 and modulate the laser beam into an image beam, which is used for imaging. The optical modulation component 12 is configured to modulate the received laser beam to obtain an image beam. The modulation process of the optical modulation component 12 may include, but is not limited to, controlling the intensity and phase of the laser beam to form the desired image information. For example, such as... Figure 3 As shown (depolarizer assembly 13 not shown), the light modulation assembly 12 may include a first homogenizing component 121, a reflector 123, a lens 124, a light valve 125, and a prism assembly 126. The light valve 125 is configured to modulate the illumination beam incident upon it into a projection beam according to the image signal, and direct the projection beam toward the lens 14. The first homogenizing component 121 and the light valve 125 are arranged sequentially along the beam propagation direction. The first homogenizing component 121 is configured to homogenize the illumination beam incident upon it and then direct it toward the light valve 125.

[0060] In some embodiments, the first light-homing component 121 is a light guide. This light guide receives the illumination beam provided by the light source 11 and homogenizes the illumination beam. In some embodiments, the light outlet of the light guide is rectangular. The light guide can shape the light beam spot so that the shape of the light beam spot matches the shape of the light valve. In some embodiments, the first light-homing component 121 can also be a compound eye lens.

[0061] The light valve 125 can be a reflective light valve. The light valve 125 includes multiple reflective sheets, each corresponding to a pixel in the projected image. For example, depending on the projected image to be displayed, the reflective sheet of the light valve 125 corresponding to the pixel to be displayed in a bright state can reflect a light beam to the lens 14. The light beam reflected to the lens 14 is called the projection beam. In this way, the light valve 125 can modulate the illumination beam to obtain the projection beam, and use the projection beam to display the image.

[0062] In some embodiments, the light valve 125 is a digital micromirror device (DMD). A DMD includes multiple (e.g., thousands) of tiny reflective mirrors that can be individually driven and rotated. These tiny reflective mirrors can be arranged in an array. Each tiny reflective mirror (e.g., each micromirror) corresponds to a pixel in the projected image to be displayed.

[0063] See also Figure 2 In some embodiments, the laser projection device 1 may further include an illumination mirror assembly located between the light valve 125 and the first light homogenizing component 121. The illumination mirror assembly includes a reflector 123, a lens 124, and a prism assembly 126. The light beam homogenized by the first light homogenizing component 121 can be directed to the light valve 125 through the illumination mirror assembly.

[0064] The illumination beam emitted from the first light-diffusing component 121 is directed towards the reflector 123, which reflects the illumination beam to the convex lens 124. The convex lens 124 converges the illumination beam into the prism assembly 126, which then reflects the illumination beam into the light valve 125.

[0065] The depolarizer assembly 13 is disposed in the laser display optical path between the light source 11 and the light-emitting side of the light modulation assembly 12. For example, in... Figure 1 In the tri-color laser shown, the depolarizer assembly 13 can be disposed in the optical path between the dichroic filter and the optical guide. It can also be disposed on the light-emitting side of the light source to suppress speckle on the laser beam emitted from the light source. Figure 3 In the case where the first light-uniforming component 121 is a compound eye lens, the depolarizer assembly 13 can also be disposed on the light-emitting side of the light source, the light-incident side of the compound eye lens, and the optical path between the lens 124 and the light valve 125.

[0066] The depolarizer assembly 13 supports rotation about the beam propagation direction. The depolarizer assembly 13 rotates about the beam propagation direction. Figure 2 In the F direction, the rotation angle of the depolarizer assembly 13 refers to the polarization rotation angle.

[0067] Specifically, such as Figure 2 As shown, the laser beam provided by the light source 11 is modulated into an image beam by the optical modulation component 12. Through the laser display optical path between the light source 11 and the light output side of the optical modulation component 12, the polarized light undergoes birefringence and interference effects inside the depolarizer component 13, thereby converting the polarized light into randomly polarized light. The birefringence caused by the stress of the lens in the optical modulation component 12 usually has a fixed fast and slow axis direction, which will affect the polarization state of the light passing through the lens. However, the depolarization mechanism of the depolarizer component 13 is fixed and cannot cope with the polarization state change problem caused by this stress, thus affecting the depolarization effect. In the embodiments provided in this application, the depolarizer assembly 13 supports rotation about the beam propagation direction when in operation. During the rotation of the depolarizer assembly 13, the polarization direction of the light changes relative to the axis of stress birefringence each time the beam passes through the lens. In this way, the phase delay caused by stress will produce different effects in different directions. After time averaging, they cancel each other out, which can reduce the negative impact of the birefringence effect of lens stress on the depolarization effect of the depolarizer assembly 13. This will further reduce the speckle contrast and improve the speckle suppression effect, which is beneficial to the efficient speckle suppression of small-sized projection laser equipment.

[0068] In one exemplary technology, the laser projection device 1 further includes a heat dissipation device (not shown), which is disposed near the light source 11 to dissipate heat from the light source 11. By providing the heat dissipation device, the light source 11 can be cooled in a timely manner when it is working, so as to maintain the stable operation of the light source 11.

[0069] In one exemplary technique, when the optical modulation component 12 includes a digital micromirror device, Figure 2 The depolarizer assembly 13 rotates within a range of -5° to 5° about the beam propagation direction.

[0070] The depolarizer assembly 13 can control its optical elements (such as a dual-wedge depolarizer) to periodically deflect within a range of ±5° via a built-in piezoelectric ceramic driver or a micro stepper motor. For example, when a built-in piezoelectric ceramic driver is used, the rotation angle is controlled by the voltage or pulse signal of the piezoelectric ceramic driver to ensure that the motion accuracy of the depolarizer assembly 13 is within ±0.1°. Specifically, the driving frequency can be in the range of 50~200Hz, and the incident direction of the laser beam is randomized in time through high-frequency dynamic adjustment.

[0071] The micromirrors in a digital micromirror device (DMD) are typically designed to deflect at ±12° or ±17° (such as the TI DLP series). Their effective reflection efficiency is sensitive to the angle of the incident beam. By limiting the rotation range of the depolarizer assembly 13 to ±5°, it can be ensured that the angle between the principal direction of the incident beam and the normal of the micromirror is within ±5°. When the angle between the incident beam and the normal of the micromirror is within ±5°, the reflection efficiency is >90%. When it exceeds this range, the reflection efficiency of the DMD drops sharply to <70%. Therefore, rotating the depolarizer assembly 13 within the range of -5° to 5° about the beam propagation direction can avoid the decrease in DMD reflection efficiency or the distortion of the light spot due to the incident angle exceeding the limit, thereby improving the display quality.

[0072] In one exemplary technology, such as Figure 2 As shown, the rotation angle of the depolarizer assembly 13 is greater than 0 degrees and less than or equal to 90 degrees.

[0073] When the rotation angle is 0 degrees and 90 degrees, the polarized light emitted from the depolarizer assembly 13 is linearly polarized light. When the rotation angle is selected between 0 degrees and 90 degrees, such as Figure 4 As shown, the polarized light emitted from the depolarizer assembly 13 will become either circularly polarized light or elliptically polarized light.

[0074] In an optional embodiment, the rotation angle of the depolarizer assembly 13 can be one of 15 degrees, 45 degrees, 75 degrees, and 90 degrees.

[0075] When the rotation angle of the depolarizer assembly 13 is set to 15 degrees, the polarized light emitted from the depolarizer assembly 13 becomes elliptically polarized light. Compared with the rotation angle of 0 degrees, the change in polarization state reduces the coherence between laser beams, resulting in some improvement in display effect, brightness uniformity, and color accuracy.

[0076] When the rotation angle of the depolarizer assembly 13 is set to 45 degrees, the polarized light emitted by the depolarizer assembly 13 is closer to circularly polarized light. In terms of speckle suppression, the speckle suppression effect is better than that when the rotation angle is 15 degrees, and the uneven brightness caused by speckle on the projected image is significantly improved. At this time, when the user observes the display image from different angles, the overall brightness and color of the image remain relatively stable over a wider viewing angle range, further enhancing the visual experience.

[0077] When the rotation angle of the polarizer assembly 13 is set to 75 degrees, the speckle effect on the image is minimal, and the image appears clear and uniform. In terms of viewing angle characteristics, compared to 45 degrees, the image seen by users in different positions over a wider angle range exhibits high consistency in brightness and color.

[0078] In an optional embodiment, the depolarizer assembly 13 is rotated 90 degrees, and the polarized light emitted from the depolarizer assembly 13 is linearly polarized light, which has a high degree of speckle suppression and the best speckle suppression effect. The picture quality is extremely high, and there are no problems such as uneven brightness or color distortion caused by speckle, whether in the center or at the edge of the picture. The brightness is uniform and the color reproduction is accurate. At the same time, the viewing angle characteristics are also in an optimal state, and viewers from all angles can obtain a clear and high-quality visual experience, ensuring the overall display effect of the large-screen display system.

[0079] In one implementation, the depolarizer assembly 13 includes a depolarizer that can employ a depolarizing plate to achieve polarization rotation.

[0080] In one exemplary technique, depolarizing waveplates are typically made of birefringent materials to reduce polarization effects by introducing different phase delays.

[0081] For example, the depolarizing plate is a double wedge prism made of birefringent material. In this case, the beam angle is deflected by relative rotation:

[0082]

[0083] Where θ1 and θ2 are the deflection angles of the two single prisms, respectively. The rotational phase difference between the two single prisms is determined by adjusting... It can achieve continuous deflection within a range of ±5°.

[0084] In one exemplary technique, the depolarizer may include one of the following depolarizers: a rotating depolarizer, a wedge depolarizer, a Lyot depolarizer, or a multilayer coating depolarizer.

[0085] In one embodiment, a rotating depolarizer is selected as the depolarizer. The rotating depolarizer mainly includes a mechanically rotatable optical element and a motor or other driving device. The optical element can be in the form of a wedge or waveplate. The motor or other driving device drives the optical element to rotate mechanically. When a light beam is incident on the rotating optical element, the optical element has different effects on the polarization state of the beam at different rotation angles. As the optical element continues to rotate, the polarization state at different times can be averaged, thereby effectively reducing the polarization effect. This significantly improves problems such as uneven brightness and color deviation caused by the polarization effect, thus enhancing the overall display quality.

[0086] In one embodiment, a wedge-shaped depolarizer is used as the depolarizer. The wedge-shaped depolarizer consists of two optical elements with different wedge angles. When a light beam enters the wedge-shaped depolarizer, the different wedge angles of the two optical elements alter the beam's propagation path. These different propagation paths cause the beam to undergo different refraction and reflection processes, thus disrupting and redistributing the beam's polarization state. This ultimately reduces polarization, effectively eliminating problems such as image blurring and abnormal contrast caused by polarization, resulting in a clearer and more realistic laser projection display.

[0087] In one embodiment, a Lyot depolarizer is selected as the depolarizer. The Lyot depolarizer in this embodiment is constructed based on a clever combination of multiple birefringent crystals. When the light beam enters the Lyot depolarizer, it passes through different birefringent crystals sequentially. Because each crystal has a different optical path difference, as the beam propagates within it, its two mutually perpendicular polarization components undergo different phase changes based on these different optical path differences. This results in the polarization state of the beam being readjusted and optimized after the continuous action of multiple crystals, ultimately eliminating the polarization effect and improving the accuracy and clarity of the projected display.

[0088] In one embodiment, a multi-layer coated depolarizer is used. Multi-layer coated depolarizers reduce polarization effects by applying multiple coatings to an optical surface, and are commonly used in mirrors and lenses. These coatings are carefully matched and designed in terms of material, thickness, and refractive index, and they are stacked together to form a unified depolarization structure. When a light beam strikes the surface of an optical element with multiple coatings, the beam undergoes multiple reflections, refractions, and interferences between the coatings. Through these complex optical interactions, the polarization state of the beam is gradually changed and optimized, ultimately effectively reducing polarization effects. This avoids beam loss and degraded projected image quality caused by polarization, improving image clarity and contrast.

[0089] In one exemplary technique, the depolarizer assembly 13 includes a depolarizer comprising two anisotropic crystals.

[0090] Anisotropy in optical crystals refers to the different optical properties exhibited by a crystal in different directions. This phenomenon is mainly due to the orientation of the arrangement of atoms or molecules within the crystal.

[0091] When the laser beam emitted by the light source 11 is incident on the depolarizer assembly 13, the laser beam passes through the anisotropic crystal. The refractive index of the light changes with the direction of light propagation within the crystal, resulting in different propagation speeds of light in different directions within the crystal, thus affecting the propagation path and phase of the light. This anisotropic refractive index characteristic makes the propagation process of light within the crystal more complex and controllable, allowing us to change the polarization state and propagation characteristics of the light according to our desired method, which is beneficial for achieving high-precision and efficient depolarization control. Under the optical action within the crystal, the polarization state of the two crystals is significantly changed. The synergistic effect of the two crystals can achieve efficient polarization elimination of light of different wavelengths over a wide spectral range, greatly improving the speckle suppression effect. Combined with the rotation of the depolarizer, it can further suppress the birefringence effect caused by stress in the light modulation assembly 12, ensuring the depolarization effect of the depolarizer, effectively improving various quality defects in the final display image caused by polarization problems, making the image clearer, more uniform, and with accurate color reproduction.

[0092] Optionally, in one embodiment, the anisotropic crystal may be one of calcite, quartz, and mica.

[0093] In one embodiment, the optical axis angles of the two anisotropic crystals are not equal; for example, neither of the optical axis angles of the two crystals is 0°. Since light changes its polarization state according to a specific law after passing through the first crystal, if the optical axis angle of the second crystal is the same, the light in the second crystal will only continue to change its polarization state in a similar way, and it cannot achieve diversified polarization adjustment effects. However, when the optical axis angles of the two crystals are not equal, for example, one crystal's optical axis makes an angle of α° with a reference direction, and the other's is β° (α≠β and neither is 0°), when light passes through these two crystals successively, it will undergo different polarization decomposition, phase change, and propagation path change processes according to the birefringence characteristics, refractive index anisotropy, and other optical properties corresponding to their different optical axis directions. This allows for the control of the polarization state of the incident light from multiple dimensions and in different ways, thereby more effectively eliminating or converting the polarization state, which is beneficial for achieving efficient polarization elimination over a wide spectral range.

[0094] In one exemplary technique, both anisotropic crystals are wedge-shaped crystals, and the wedge angle of the wedge-shaped crystals ranges from 0 degrees to 10 degrees; and / or, the difference in the optical axis angle between the two wedge-shaped crystals is greater than 0 degrees and less than 90 degrees.

[0095] Specifically, when a beam of light enters an anisotropic wedge crystal, it splits into two beams with mutually perpendicular polarization directions: the ordinary ray (o-ray) and the extraordinary ray (e-ray). These two beams propagate at different speeds within the crystal, resulting in a phase difference after they have traveled a certain distance. This phase difference alters the polarization state of the beam; for example, linearly polarized light may become elliptically or circularly polarized, depending on the magnitude of the phase difference and the initial polarization state. The crystal's refractive index varies in different directions, meaning that light propagating in different directions will have different propagation speeds within the crystal. For a beam of light propagating in a wedge crystal, different parts may propagate in different directions, thus being affected by different refractive indices, further altering the polarization state. In other words, this refractive effect of the wedge crystal, combined with its anisotropy, effectively changes the polarization state of the light beam.

[0096] When two wedge-shaped crystals are combined, the refraction effect alters the propagation path of the light beam within the crystal, increasing the opportunity for anisotropic interaction between the light and the crystal. During this change in propagation path, anisotropic properties such as birefringence, phase difference, and refractive index anisotropy continuously adjust the polarization state of the beam. For example, refraction causes the direction of light propagation within the crystal to constantly change. Birefringence and refractive index anisotropy in different propagation directions continuously affect the propagation of ordinary and extraordinary rays, accumulating phase difference and effectively altering the polarization state of the beam. This further enhances the effect of eliminating or converting the polarization of incident light, thus achieving efficient polarization elimination.

[0097] When the wedge angle is not 0 degrees, the light beam will refract upon entering and exiting the wedge-shaped crystal. If the wedge angle is too large, the refraction angle of the beam will be too large, which may cause some light rays to undergo total internal reflection at the crystal surface and fail to enter the crystal, or deviate from the expected optical path upon exiting the crystal, resulting in light energy loss. By limiting the wedge angle to the range of 0-10 degrees, excessive beam deviation or drastic changes in polarization state are avoided, which helps maintain the relative parallelism of the beam. This allows for effective modification of the polarization state while minimizing light energy loss and improving the efficiency of the optical system. In addition, a wedge angle of 0 to 10 degrees is relatively easy to achieve. A smaller wedge angle means that the propagation path of the beam in the crystal is relatively easier to predict and control. During the debugging and calibration of the optical system, the difficulty of adjusting the optical path can be reduced without significantly increasing manufacturing costs or complexity, thereby improving the stability and reliability of the system. Furthermore, a smaller wedge angle also makes it easier to ensure the flatness of the crystal and the quality of the optical surface.

[0098] In addition, a larger wedge angle may introduce more aberrations, such as spherical aberration and chromatic aberration, which will affect the imaging quality of the optical system. A wedge angle of 0 to 10 degrees can ensure that the beam can still maintain good focusing performance and imaging sharpness after passing through the wedge crystal.

[0099] If the optical axes of two crystals are perfectly parallel (with an angular difference of 0 degrees), their effects on the polarization of the beam may cancel each other out, resulting in poor depolarization. However, when the optical axis angles of the two wedge-shaped crystals differ, the polarization state of the beam changes after passing through the first crystal. When it enters the second crystal, the different optical axis direction of the second crystal further adjusts the already changed polarization state. Therefore, by setting the optical axis angle difference, it is possible to achieve conversion between various polarization states, such as from linearly polarized light to elliptically polarized light, and then further to a state close to unpolarized light, thereby more effectively eliminating the polarization of the incident beam.

[0100] However, if the angle difference is too large (close to 90 degrees or greater), it may lead to excessive interference effects, affecting the transmission and polarization state of the beam. By constraining the angle difference between the optical axes of the two wedge-shaped crystals to be greater than 0 degrees and less than 90 degrees, effective polarization conversion or elimination can be achieved.

[0101] In one embodiment of the technology, such as Figure 5 As shown, two wedge-shaped crystals W1 and W2 constitute a dual-wedge depolarizer. The front surface of wedge-shaped crystal W1 lies within the XOY plane, and the rear surface of wedge-shaped crystal W2 is parallel to the XOY plane. C1 and C2 are the optical axes of the two wedge-shaped crystals W1 and W2, respectively, which are parallel to the XOY plane and make angles θ1 and θ2 with the X-axis, respectively. In this embodiment, θ1 is not equal to θ2, that is, the optical axes of the two wedge-shaped crystals are not parallel. This avoids the polarization effects of the two wedge-shaped crystals canceling each other out when the optical axes are parallel, resulting in poor depolarization performance.

[0102] Since wedge crystals are not dependent on specific wavelengths of light, dual-wedge depolarizers can operate over a wide spectral range, supporting the processing of various wavelengths of light from ultraviolet to infrared, thus maintaining stable performance in different spectral regions.

[0103] In one embodiment, for the different wavelength characteristics of the red, green, and blue primary color lasers in the laser projection device 1, the dual-wedge depolarizer can be selected from dual-wedge materials with wide-band transmission characteristics, such as dual-wedge materials that support a spectral range of 220 nm. With this material selection, the dual-wedge depolarizer can effectively perform polarization disordering in the wavelength range of red, green, and blue primary color lasers from 440 nm (the short-wavelength end of blue laser) to 660 nm (the long-wavelength end of red laser), that is, within the wavelength range of red, green, and blue primary color lasers, thereby achieving efficient depolarization control and suppressing laser speckle.

[0104] In an optional embodiment, the dual-wedge depolarizer may be selected from dual-wedge materials that support the 430-670nm range, which covers most of the spectral region visible to the human eye. While ensuring effective depolarization, it allows the laser projection device to better reproduce various colors, especially some colors close to the edge of the spectrum, thereby improving the overall color performance and maintaining color fidelity and brightness balance.

[0105] In one exemplary technology, such as Figure 6 As shown, when the depolarizer assembly 13 supports the reflection of the incident beam based on the incident surface, the laser projection device 1 also includes a reflective film layer 14.

[0106] The reflective film layer 14 is attached to the side of the depolarizer assembly 13 away from the incident light.

[0107] Alternatively, a reflective film layer 14 can be provided on one side of the depolarizer assembly 13 as a reflective surface. When a beam of light incident on the depolarizer assembly 13 enters the assembly, it is reflected when it reaches the interface where the reflective film layer 14 is located. The reflected beam then passes through the depolarizer assembly 13 again, meaning the beam undergoes two propagation processes within the assembly. During these two propagation processes, the beam interacts with the material of the depolarizer assembly 13, continuously changing its polarization state. Since these two propagation paths are completed within the same depolarizer assembly 13, from an overall perspective, only half the original thickness of the depolarizer assembly 13 is needed to achieve the same polarization phase change as without the reflective film layer. Based on this, the laser projection device 1 provided in this embodiment can reduce the thickness of the depolarizer assembly 13 by half by adding the reflective film layer 14, which is beneficial for the small-size design of the depolarizer assembly 13 and its application in small-size laser projection devices.

[0108] In one exemplary technique, the incident angle of the laser beam onto the depolarizer should not be too high. When the laser beam is incident on the depolarizer at a large angle, some of the light may deviate from the originally designed optical path and fail to effectively participate in the depolarization process. An excessively high incident angle also increases the likelihood of beam scattering within the depolarizer. Scattering not only results in a significant loss of light energy but also creates background noise in the laser projection system, affecting the final image quality and display effect. By limiting the incident angle to within -10° to 10°, these adverse effects can be reduced, improving the system's stability and efficiency.

[0109] Furthermore, high-angle incident light can increase the contact area and collision probability between the beam and the depolarizer surface, thereby increasing the risk of optical damage. Limiting the incident angle to within -10° to 10° can reduce this risk and protect the depolarizer's lifespan.

[0110] In one exemplary technique, the reflective film layer 14 is made of metal or dielectric coating.

[0111] Among them, metal coatings have high reflectivity. For example, silver (Ag) and aluminum (Al) are common materials used for metal coatings. Silver has extremely high reflectivity in the visible light band, reaching over 95%; aluminum has good reflectivity in the ultraviolet, visible, and near-infrared bands, with a reflectivity typically reaching around 90%. High reflectivity means that most of the incident light can be reflected back into the depolarizer assembly 13, allowing the beam to propagate multiple times within the depolarizer assembly 13. This fully utilizes the optical characteristics of the depolarizer assembly 13 to change the polarization state of the beam, thereby improving depolarization efficiency.

[0112] Furthermore, the metal coating can maintain high reflectivity over a wide spectral range. Laser projection devices involve red, green, and blue primary color lasers, with a wide wavelength range (e.g., from 440-660nm). The metal coating can effectively reflect light across this broad spectral range, ensuring that different colors of laser light receive proper depolarization treatment in the depolarizer assembly 13. This guarantees the stability and consistency of the laser projection device 1 under different colors of light, which is beneficial for improving the color reproduction and brightness balance of the projected image.

[0113] In addition, the preparation process of metal coating is relatively simple, and the equipment and production costs are low, which helps to improve the market competitiveness of products.

[0114] Dielectric coatings utilize the interference effect of light to achieve high reflectivity. During the reflection process, dielectric coatings reduce light energy absorption loss, allowing more light energy to be reflected back to the depolarizer assembly 13 for polarization adjustment. Especially for high-power laser projection equipment, low-absorption-loss dielectric coatings can avoid film heating caused by light absorption, reducing the risk of optical performance changes and film damage due to thermal effects, thus ensuring system stability and reliability.

[0115] Furthermore, dielectric coatings can resist the effects of chemical corrosion and environmental factors. Under different working environments, such as high temperature, high humidity, and environments with chemical gases, the performance of dielectric coatings is relatively stable and they are not prone to chemical reactions that could damage the film or degrade its performance. This allows the depolarizer assembly 13 to maintain stable optical performance over a long period of time under complex working conditions, improving the reliability and adaptability of the product.

[0116] In one exemplary technique, the material of the metal coating includes at least one of aluminum, silver, and gold; and / or, the thickness of the metal coating ranges from 10 nm to 999 nm; and / or, the material of the dielectric coating includes a dielectric material; and / or, the thickness of the dielectric coating is one-quarter or one-half of the wavelength of the corresponding laser beam.

[0117] Aluminum and silver exhibit excellent reflectivity in the visible and near-infrared bands; details regarding their reflectivity can be found in the descriptions of the aforementioned embodiments. Their excellent reflectivity for three-color lasers helps reduce the thickness of the depolarizer region in three-color laser products. Gold demonstrates excellent reflectivity in the near-infrared band, with a reflectivity up to 98%. For laser applications involving the near-infrared band in laser projection equipment, gold coatings can be used to effectively reflect this light, meeting the depolarization requirements of specific wavelength lasers and broadening the applicable spectral range of the depolarizer assembly 13.

[0118] The thickness of the metal coating used in laser projection equipment 1 is typically between tens and hundreds of nanometers, depending on the required reflectivity and durability. When the metal coating thickness is above 10 nm, a continuous and complete film structure can be formed, ensuring good consistency and stability of light reflection on the film surface. Thinner films may have discontinuities or defects, leading to decreased reflectivity and increased scattering. As the film thickness increases to a certain extent (but not exceeding 999 nm), the reflectivity gradually tends to stabilize. For example, for silver coatings, the reflectivity can reach a relatively high level after the thickness reaches tens of nanometers. Further increasing the thickness can further improve the stability and uniformity of reflectivity, reducing reflection differences caused by thickness inhomogeneity. Therefore, the thickness of the metal coating can be specifically selected within the range of 10 nm to 999 nm.

[0119] Dielectric materials typically have a low light absorption coefficient, meaning that light experiences less energy loss as it propagates through the dielectric coating. Compared to metal coatings, using dielectric materials (such as silicon dioxide and aluminum oxide) can more effectively reflect light back to the depolarizer assembly 13, improving the energy utilization efficiency of the projection laser device 1. For example, some common dielectric materials, such as silicon dioxide (SiO2) and titanium dioxide (TiO2), have extremely low absorption losses in the visible and near-infrared bands, allowing most of the light to participate in the polarization adjustment process, reducing heat generation and optical performance degradation caused by light absorption.

[0120] When the thickness of the dielectric coating is one-quarter or one-half of the corresponding laser beam wavelength, constructive interference will occur between the reflected light according to the principle of optical interference, thereby enhancing the intensity of the reflected light. By rationally designing the structure of multilayer dielectric coatings, with each layer having a thickness that is an integer multiple of one-quarter of the wavelength, the reflectivity can be further improved. For example, for a green laser with a wavelength of 532nm, using a titanium dioxide dielectric coating with a thickness of 133nm (532nm / 4) and combining it with other suitable dielectric layers can achieve a reflectivity close to 100% at this wavelength, optimizing optical performance.

[0121] The human eye is sensitive to red and green light, but relatively insensitive to blue light. Based on this, in an exemplary technology, the light source 11 is used to provide red laser, green laser, and blue laser; the depolarizer assembly 13 is used to be disposed in the laser display optical path of at least one of the red and green laser beams.

[0122] By setting the depolarizer assembly 13 to depolarize at least one of the red laser and green laser beams, the coherence of the red laser and / or green laser is reduced, the speckle phenomenon of red and / or green light spots in the final projected image beam is suppressed, and the display effect is improved.

[0123] In one exemplary technology, such as Figure 7 As shown, the light source 11 includes: a red laser 111 for providing red laser light; a green laser 111 for providing green laser light; and a blue laser 111 for providing blue laser light. Figure 7 The diagram does not show the structural details of the three-color laser; it is mainly for illustrative purposes.

[0124] like Figure 7 As shown, the light source 11 also includes multiple beam combining mirror groups 112. The multiple beam combining mirror groups 112 are respectively arranged one-to-one on the output side of the red laser, green laser and blue laser to mix and reflect the incident laser light;

[0125] like Figure 7 As shown, the light source 11 also includes a beam-shrinking component 113. The beam-shrinking component 113 is used to receive the laser reflected by the beam combining mirror group 112 and to shrink the incoming laser beam before emitting it.

[0126] Among them, the target beam combining mirror group 112 is provided with a depolarizer assembly 13 on the light input side or light output side, and the target beam combining mirror group 112 is the beam combining mirror group corresponding to the red laser and / or the beam combining mirror group 112 corresponding to the green laser.

[0127] By setting a depolarizer assembly in the optical path corresponding to the red laser and / or green laser ( Figure 5 (Not shown in the image) By utilizing the depolarization capability of the depolarizer, the coherence of the red laser / or green laser is suppressed, thereby suppressing the speckle phenomenon of red and / or green light spots in the final projected image beam and improving the display effect.

[0128] In one exemplary technology, such as Figure 8 and Figure 9 As shown, a polarizer assembly 13 is provided on the incident light side of the target combining mirror group 112.

[0129] The laser beam projected by laser 111 is depolarized by depolarizer assembly 13 and then propagates to beam combiner assembly 112. After passing through beam combiner assembly 112, it propagates to beam shrinking component (e.g., Figure 8The focusing lens 1131 and the light guide 1133, and for example... Figure 9 The compound eye lens 1134 in the middle, after passing through the beam-contracting component, propagates the laser beam to the optical modulation component 12 (which may include the compound eye lens 1134 in the middle). Figure 9 Multiple illumination lens groups 122 in the lens are modulated by the light modulation component 12 to provide an image beam to the lens 20 for imaging.

[0130] In one exemplary technology, such as Figure 10 and Figure 11 As shown, a polarizer assembly 13 is provided on the light-emitting side of the target combining mirror group 112.

[0131] The laser beam projected by laser 111 propagates to beam combiner assembly 112, and after passing through beam combiner assembly 112, it enters depolarizer assembly 13. After being depolarized by depolarizer assembly 13, it propagates to beam shrinking component (e.g., Figure 10 The focusing lens 1131 and the light guide 1133, and for example... Figure 9 The compound eye lens 1134 in the middle, after passing through the beam-contracting component, propagates the laser beam to the optical modulation component 12 (which may include the compound eye lens 1134 in the middle). Figure 11 Multiple illumination lens groups 122 in the lens are modulated by the light modulation component 12 to provide an image beam to the lens 20 for imaging.

[0132] In one exemplary technique, the depolarizer assembly can be integrated with adjacent optical elements to further reduce the size of the laser projection device. For example, microstructures can be fabricated on one side of the optical element to form a depolarizer, altering the propagation path and phase of the beam.

[0133] In one exemplary technology, such as Figure 7 As shown, the beam combining mirror assembly 112 includes a reflector 1121, a dichroic filter 1122, and a diffuser 1123. The beam converging component 113 includes a focusing lens 1131, a diffuser wheel 1132, and a light guide 1133. The green laser beam projected by the green laser is reflected by the reflector 1121 and then projected onto the dichroic filter 1122. The red laser beam projected by the red laser is incident on the dichroic filter 1122. After the red and green laser beams are combined by the dichroic filter 1122, they propagate to the diffuser 1123. The beam then propagates through the diffuser 1123 to the focusing lens 1131. After being focused by the focusing lens 1131, the beam is projected onto the diffuser wheel 1132. The beam projected from the diffuser wheel 1132 continues to propagate in the light guide 1133 and then to the light modulation component 12. After being modulated by the light modulation component 12, the modulated image beam is projected onto the projection screen through the lens to display an image.

[0134] In one exemplary technology, such as Figure 7 As shown, the target beam combining lens assembly 112 includes a diffuser 1123, which is integrated with the depolarizer assembly. This integration method reduces the size of the laser projection device.

[0135] In one exemplary technology, such as Figure 6 As shown, the beam-shrinking component 113 includes a compound eye lens 1134, which is integrated with a depolarizer assembly (not shown).

[0136] In one exemplary technology, such as Figures 12-13 As shown, the light modulation assembly 12 includes: a plurality of illumination lens groups 122, and a depolarizer assembly 13 disposed in the optical path between two adjacent illumination lens groups 122.

[0137] In one exemplary technique, the depolarizer assembly includes a depolarizer and a vibration device (not shown).

[0138] The depolarizer is located on the laser display optical path between the light source 11 and the light output side of the light modulation component 12 shown in the figure. A vibration device is used to drive the depolarizer to vibrate.

[0139] By combining a vibrating device to drive the depolarizer to jitter, the beam can be deflected at the illumination end. On a time average, this is equivalent to increasing the angle of the emitted light, increasing the optical spread of the system, and achieving different polarizations of light at different times and positions. At the same time, it can also increase the system angle and optical spread, further reducing speckle.

[0140] In one embodiment, the vibrating device can be a device such as a galvanometer. The vibration angle of the galvanometer is to offset the pixel by 1 pixel, which is about 5μm. The angle is very small. Even with small displacement jitter, it can cause beam shift at the illumination end, increase the output light angle, increase the optical extension of the system, and ensure speckle suppression effect in small-size laser projection equipment application scenarios.

[0141] It should be noted that the rotation of the depolarizer assembly can be achieved by its own mechanical transmission components, or by the mechanical and control systems of the laser projection equipment. Any scheme that can achieve the depolarizer rotation function is subject to protection under this application, and will not be exhaustively listed here.

[0142] In one embodiment, a laser projection system 100 is provided, including the laser projection device 1 and the projection screen 2 described above.

[0143] By incorporating the aforementioned laser projection device 1, speckle suppression during laser propagation can be ensured, thereby guaranteeing the image display quality projected onto the projection screen 2. Furthermore, by employing the depolarizer component 13 for depolarization, compared to the traditional method using diffuser sheets and diffuser wheels, it is more conducive to the miniaturization design of the laser projection device 1 and to improving its depolarization control accuracy. This enables high-precision depolarization control of the small-size laser projection system 100, achieving high-quality projection display from the small-size laser projection system 100.

[0144] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0145] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0146] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A laser projection device, characterized in that, include: A light source used to provide a laser beam; An optical modulation component is used to receive the laser beam provided by the light source and modulate the laser beam into an image beam, the image beam being used for imaging. A depolarizer assembly is disposed in the laser display optical path from the light source to the light output side of the light modulation assembly, and the depolarizer assembly supports rotation about the beam propagation direction as an axis. A lens is used to project an image beam emitted from the light modulation component onto a display substrate to display an image.

2. The laser projection device according to claim 1, characterized in that, When the optical modulation assembly includes a digital micromirror device, the depolarizer assembly rotates about the beam propagation direction as an axis within a range of -5° to 5°.

3. The laser projection device according to claim 1, characterized in that, The rotation angle of the depolarizer assembly is greater than 0 degrees and less than or equal to 90 degrees.

4. The laser projection device according to claim 1, characterized in that, The depolarizer assembly includes a depolarizer comprising two anisotropic crystals.

5. The laser projection device according to claim 4, characterized in that, Both anisotropic crystals are wedge-shaped crystals, and the wedge angle of the wedge-shaped crystals ranges from 0 degrees to 10 degrees; and / or, the difference in the optical axis angle between the two wedge-shaped crystals is greater than 0 degrees and less than 90 degrees.

6. The laser projection device according to any one of claims 1-5, characterized in that, If the depolarizer assembly supports reflection of the incident beam based on the incident surface, the laser projection device further includes: A reflective film layer is attached to the side of the depolarizer assembly away from the incident light.

7. The laser projection device according to claim 6, characterized in that, The reflective film layer is made of metal or dielectric.

8. The laser projection device according to claim 7, characterized in that, The metal coating material includes at least one of aluminum, silver, and gold; and / or, the thickness of the metal coating ranges from 10 nm to 999 nm; and / or, the dielectric coating material includes a dielectric material; and / or, the thickness of the dielectric coating is one-quarter or one-half of the wavelength of the corresponding laser beam.

9. The laser projection device according to claim 1, 2, 3, 4, 5, 7, or 8, characterized in that, The light source is used to provide red laser, green laser and blue laser; the depolarizer assembly is used to be disposed in the laser display optical path of at least one of the red laser and the green laser.

10. The laser projection device according to claim 9, characterized in that, The light source includes: Red laser, used to provide red laser light; Green laser, used to provide green laser light; Blue laser, used to provide blue laser light; Multiple beam combining mirror groups are respectively and correspondingly arranged on the output side of the red laser, the green laser and the blue laser to mix and reflect the incident laser light; A beam-shrinking component is used to receive the laser reflected by the beam combining mirror group and to shrink the incoming laser beam before emitting it. The depolarizer assembly is provided on the light input side or light output side of the target beam combining mirror group, and the target beam combining mirror group is the beam combining mirror group corresponding to the red laser and / or the beam combining mirror group corresponding to the green laser.

11. The laser projection device according to claim 10, characterized in that, The target beam combining lens assembly includes a diffuser, which is integrated with the depolarizer assembly; or, the beam constriction component includes a compound eye lens, which is integrated with the depolarizer assembly.

12. The laser projection device according to any one of claims 1, 2, 3, 4, 5, 7, or 8, characterized in that, The optical modulation component includes: Multiple illumination lens groups, wherein the depolarizer assembly is disposed in the optical path between two adjacent illumination lens groups.

13. The laser projection device according to any one of claims 1, 2, 3, 4, 5, 7, or 8, characterized in that, The depolarizer assembly includes: A depolarizer is disposed in the laser display optical path from the light source to the light-emitting side of the light modulation component; A vibration device is used to drive the depolarizer to vibrate.

14. A laser projection system, characterized in that, Includes the laser projection device and projection screen as described in any one of claims 1-13.

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