Laser illumination module, optical projection system and smart head-mounted device

Abstract

A laser illumination module, an optical projection system and a smart head-mounted device. The laser illumination module comprises a first lens group, a fly's-eye lens (204), a second lens group, a reflector (206), a total internal reflection prism (208) and a DMD chip (209), wherein the first lens group comprises at least one of a first lens (201) and a second lens (202), and a diffuser (203); the fly's-eye lens (204) is located on a light-emergent side of the first lens group; the second lens group comprises a third lens (205) and a fourth lens (207); the reflector (206) is located on an optical path between the third lens (205) and the fourth lens (207); the total internal reflection prism (208) is located on a light-emergent side of the fourth lens (207); the DMD chip (209) is arranged adjacent to the total internal reflection prism (208); the fourth lens (207) can move along the optical axis thereof, so as to change the spacing between the fourth lens (207) and the third lens (205) and the spacing between the fourth lens (207) and the total internal reflection prism (208), thereby achieving zooming; and the DMD chip (209) receives zoomed illumination light, enabling the laser illumination module to match DMD chips (209) of different sizes.

Description

Laser lighting modules, optical projection systems, and smart head-mounted devices

[0001] This application claims priority to Chinese Patent Application No. 202411996483.5, filed with the Chinese Patent Office on December 31, 2024, entitled "Laser Lighting Module, Optical Projection System and Smart Head-Mounted Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical display technology, and more specifically, to a laser illumination module, an optical projection system, and a smart head-mounted device. Background Technology

[0003] With the rapid development of the projection product market, laser projectors, with their advantages of vibrant colors, high color gamut, and compact size, have gradually gained widespread popularity among consumers. As a core component of laser projectors, the laser illumination module has a high design complexity, directly affecting key indicators such as luminous flux, contrast ratio, and image uniformity. Among these components, the DMD (Digital Micromirror Device, or light valve) is the main component of the laser illumination module. Its size, micromirror deflection angle, and other parameters determine the design of the relay system in the illumination module, such as the radius of curvature, thickness, and spacing of the lenses.

[0004] However, due to the wide variety of DMD types and models, laser lighting modules also exhibit diverse characteristics. This not only increases R&D costs but also makes it difficult to share laser lighting modules across different platforms, resulting in redundant waste of resources. Therefore, how to solve the problem of the large number of laser lighting modules and their incompatibility has become a technical challenge that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a new technology solution for a laser lighting module, an optical projection system, and a smart head-mounted device.

[0006] In a first aspect, this application provides a laser lighting module, the laser lighting module comprising:

[0007] The first lens group includes at least one of a first lens and a second lens, and a diffuser.

[0008] The compound eye lens is located on the light-emitting side of the first lens group;

[0009] The second lens group includes the third lens and the fourth lens;

[0010] A reflector is located in the optical path between the third lens and the fourth lens, and is used to change the direction of the optical path;

[0011] An internal total internal reflection prism is located on the light-emitting side of the fourth lens;

[0012] The DMD chip is disposed adjacent to the internal total reflection prism;

[0013] The fourth lens can move along its optical axis to change its distance from the third lens and the internal total internal reflection prism, thereby achieving zoom.

[0014] The DMD chip receives the zoomed illumination light, enabling the laser illumination module to be compatible with DMD chips of different sizes.

[0015] Optionally, the laser illumination module satisfies: 1.2≤|f1 / f2|≤1.5; where f1 and f2 are the focal lengths of the laser illumination module corresponding to the DMD chip being 0.39 inches and 0.47 inches, respectively.

[0016] Optionally, when the first lens group includes a first lens and a second lens, the diffuser is located between the first lens and the second lens.

[0017] Optionally, the first lens, the second lens, the third lens, and the fourth lens are glass spherical lenses.

[0018] Optionally, when the DMD chip is 0.39 inches, the F-number of the laser illumination module is F1, and when the DMD chip is 0.47 inches, the F-number of the laser illumination module is F2, then F1 < F2.

[0019] Optionally, when the DMD chip is 0.39 inches, the effective optical aperture of the fourth lens is D1, and when the DMD chip is 0.47 inches, the effective optical aperture of the fourth lens is D2, and D1 = D2.

[0020] Optionally, the optical power of the first lens, the second lens, the third lens, and the fourth lens are all positive.

[0021] Optionally, the first lens is a convex-concave lens, the second lens is a concave-convex lens, and the third and fourth lenses are biconvex lenses.

[0022] Optionally, the compound eye lens is a double-sided compound eye with an incident light angle ≤10° and a thickness ≤5mm.

[0023] Optionally, the first lens, the second lens, and the third lens are arranged along the first optical axis, and the fourth lens is arranged along the second optical axis, with the first optical axis and the second optical axis forming an angle.

[0024] The reflector is tilted to project the light emitted from the third lens onto the fourth lens.

[0025] Optionally, the second lens group further includes a fifth lens, which is located between the third lens and the fourth lens.

[0026] Optionally, the illumination module further includes a laser light source located on the light-incident side of the first mirror group.

[0027] Secondly, this application provides an optical projection system, the optical projection system comprising:

[0028] The laser lighting module as described in the first aspect; and

[0029] A projection lens, located on the light-emitting side of the internal total internal reflection prism.

[0030] Thirdly, this application provides a smart head-mounted device, the smart head-mounted device comprising:

[0031] The outer casing; and

[0032] The optical projection system as described in the second aspect.

[0033] The beneficial effects of this application are as follows:

[0034] To address the problems existing in the prior art, this application proposes a variable-focus laser illumination module that is compatible with DMD chips of different sizes. By adjusting the focal length of the relay section, the laser illumination module of this application can flexibly change the size of the light spot incident on the DMD chip and the incident angle, thereby achieving compatibility with DMD chips of different sizes, significantly improving the versatility of laser projection products, and effectively reducing development and manufacturing costs.

[0035] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0037] Figure 1 is a schematic diagram of the optical projection system provided in an embodiment of this application;

[0038] Figure 2 is a simulation diagram of the optical projection system provided in an embodiment of this application;

[0039] Figure 3 is a comparison of the system layout of the optical projection system provided in the embodiments of this application with a 0.47-inch DMD chip (left) and a 0.39-inch DMD chip (right);

[0040] Figure 4 is a dot array diagram of the optical projection system under a 0.47-inch DMD chip, shown on the left side of Figure 3;

[0041] Figure 5 is a dot array diagram of the optical projection system under a 0.39-inch DMD chip, shown on the right side of Figure 3;

[0042] Figure 6 is a light trace diagram of the image plane of the laser illumination module according to an embodiment of this application;

[0043] Figure 7 shows the relative illumination of the optical projection system under a 0.47-inch DMD chip, as shown on the left side of Figure 3.

[0044] Figure 8 is a relative illumination diagram of the optical projection system under a 0.39-inch DMD chip, shown on the right side of Figure 3.

[0045] Explanation of reference numerals in the attached drawings: 100, laser source; 201, first lens; 202, second lens; 203, diffuser; 204, compound eye lens; 205, third lens; 206, reflector; 207, fourth lens; 208, internal total reflection prism; 209, DMD chip; 300, projection lens. Detailed Implementation

[0046] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0047] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0048] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0049] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0050] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0051] The laser illumination module, optical projection system, and smart head-mounted device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0052] According to one embodiment of this application, a laser illumination module is provided. Referring to Figures 1 and 2, the laser illumination module includes a first mirror group, a compound eye lens 204, a second mirror group, a reflector 206, an internal total reflection prism 208, and a DMD chip 209. The first mirror group includes at least one of a first lens 201 and a second lens 202, and a diffuser 203. The compound eye lens 204 is located on the light-emitting side of the first mirror group. The second mirror group includes a third lens 205 and a fourth lens 207. The reflector 206 is located on the third lens 205. 5. In the optical path between the third lens 205 and the fourth lens 207, the direction of the optical path is changed; the internal total internal reflection prism 208 is located on the light-emitting side of the fourth lens 207; the DMD chip 209 is disposed adjacent to the internal total internal reflection prism 208; wherein, the fourth lens 207 can move along its optical axis to change its interval with the third lens 205 and the internal total internal reflection prism 208, thereby achieving zoom; the DMD chip 209 receives the zoomed illumination light, so that the laser illumination module can match DMD chips 209 of different sizes.

[0053] The laser illumination module provided in this application embodiment achieves zoom functionality in the relay section through a specially designed optical path layout, and the entire laser illumination module is compatible with DMD chips 209 of different sizes. The laser illumination module provided in this application embodiment consists of several key optical components, which are described below.

[0054] The laser illumination module provided in this application includes a first mirror group disposed adjacent to the laser source 100 on the incident light side. Referring to Figures 1 and 2, the first mirror group may include one or two lenses. For example, the first mirror group may include only the first lens 201, or only the second lens 202, or both the first lens 201 and the second lens 202. The number of lenses can be flexibly adjusted as needed.

[0055] The first mirror assembly also includes a diffuser 203, which is, for example, a vibrating diffuser.

[0056] The combination of the first lens group performs preliminary shaping and amplification of the illumination light (laser light) emitted by the laser source 100, while the diffuser 203 effectively suppresses laser speckle, ensuring the uniformity and quality of the light.

[0057] The laser illumination module provided in this application includes a compound eye lens 204 located behind the first lens group. The compound eye lens 204 is used to further homogenize and shape the incident illumination light, making the illumination light more uniform and consistent, and providing a good foundation for subsequent precise control.

[0058] The compound eye lens 204 can be, for example, a bifacial compound eye.

[0059] The laser illumination module provided in this application includes a second mirror group, which may include 2 to 3 lenses. Specifically, referring to Figures 1 and 2, the second mirror group mainly consists of a third lens 205 and a fourth lens 207. This combination relays and regulates the illumination light homogenized by the compound eye lens 204, ensuring that the illumination light can accurately strike the DMD chip 209. The reflector 206 is cleverly positioned in the optical path between the third lens 205 and the fourth lens 207 to change the direction of the optical path, making the overall optical path layout more compact and reasonable.

[0060] The laser illumination module provided in this application includes an internal total internal reflection prism 208. Referring to Figures 1 and 2, the internal total internal reflection prism 208 is located on the light-emitting side of the fourth lens 207. It uses the principle of total internal reflection to effectively separate the illumination light incident on the DMD chip 209 from the projection light entering the projection lens 300, thereby avoiding mutual interference of light.

[0061] In the laser illumination module provided in this application embodiment, the most crucial aspect is that the fourth lens 207 is designed to move along its optical axis to change its spacing from the third lens 205 and the internal total internal reflection prism 208. This design enables the relay section to perform zoom functionality; by adjusting the focal length, the size of the light spot incident on the DMD chip 209 and the incident angle can be changed, thereby matching DMD chips 209 of different sizes. This design not only improves the versatility and modularity of laser projection devices but also significantly reduces development and manufacturing costs.

[0062] It should be particularly noted that, referring to Figure 3, in this application, the third lens 205, the fourth lens 207, and the reflector 206 located between them together form the relay optical path in the entire illumination module. The main function of this optical path is to shape the illumination light incident on the DMD chip 209 (image processing chip) and adjust its incident angle. In this process, the third lens 205 first performs preliminary shaping of the illumination light, then the illumination light is reflected by the reflector 206, and then further adjusted by the fourth lens 207 to ensure that the illumination light can be projected onto the DMD chip 209 in the best condition. At the same time, the internal total internal reflection prism 208 plays an important role, separating the illumination light incident on the DMD chip 209 from the beam entering the projection lens 300, avoiding interference between the two. As the core component of image processing, the DMD chip 209, through its millions of precision micromirrors, performs the final adjustment of the illumination light, thereby achieving high-quality image output.

[0063] The laser lighting module provided in this application embodiment can process the lighting light emitted by the peripheral laser light source 100 and project it onto the projection lens 300.

[0064] The laser illumination module provided in this application embodiment achieves a zoom function by moving the fourth lens 207 along its optical axis, changing its spacing with the third lens 205 and the internal total internal reflection prism 208. This zoom function allows the laser illumination module to be compatible with DMD chips 209 of different sizes, improving the module's compatibility and flexibility. The laser illumination module of this application embodiment is compatible with DMD chips of various sizes, such as 0.39 inches and 0.47 inches. Improved compatibility reduces development costs and avoids the need to redesign the illumination module for different DMD chips.

[0065] The laser illumination module provided in this application embodiment, in which the first lens group, the second lens group, the compound eye lens 204, the reflector 206, the internal total reflection prism 208, and the DMD chip 209 work together to achieve precise control of the optical path. Precise optical path control ensures that light can be efficiently and accurately projected onto the DMD chip 209, improving image quality.

[0066] The compound eye lens 204 homogenizes and shapes the incident illumination light, improving the uniformity and consistency of the lighting effect. All components in the laser lighting module, including lenses and reflectors 206, are meticulously designed to ensure optimal light transmission and projection.

[0067] It should be noted that, in this application, the fourth lens 207 is designed to move along its optical axis to change its spacing from the third lens 205 and the inner total internal reflection prism 208, thereby achieving zoom. Referring to Figures 1 and 2, the fourth lens 207 and the third lens 205 are not located on the same optical axis; in this case, the spacing between them refers to the straight-line distance from the center of the fourth lens 207 to the center of the third lens 205. The spacing between the fourth lens 207 and the inner total internal reflection prism 208 refers to the air gap between them.

[0068] In summary, this application reduces the cost of redeveloping laser lighting modules for different products by achieving zoom capability and compatibility with multiple DMD chips. The increased versatility and modularity of the laser lighting module simplifies production and maintenance processes. Researchers can quickly develop various laser projection products of different sizes based on this laser lighting module. The versatility of the laser lighting module reduces repetitive design work and improves R&D efficiency.

[0069] In some examples of this application, the laser illumination module satisfies: 1.2≤|f1 / f2|≤1.5; where f1 and f2 are the focal lengths of the laser illumination module corresponding to the DMD chip 209 being 0.39 inches and 0.47 inches, respectively.

[0070] The setting of the focal length ratio range proposed in this example of the application is described in detail below.

[0071] By setting the focal length ratio range between 1.2 and 1.5 (including the two endpoints of 1.2 and 1.5) as described above, it is ensured that when the size of the DMD chip 209 is switched from 0.39 inches to 0.47 inches, the laser illumination module provided in this application embodiment can maintain a certain zoom capability and optical performance stability.

[0072] Within the focal length ratio range mentioned in this example of the application, by adjusting the position of the relay part of the laser illumination module, such as the fourth lens 207, the corresponding changes in the spot size and incident angle can be achieved, thereby meeting the illumination requirements of DMD chips 209 of different sizes.

[0073] Furthermore, the setting of the focal length ratio range in this example also takes into account the balance of optical performance, including key indicators such as illumination uniformity, spot size control, and telecentricity, to ensure that image quality is not affected.

[0074] In the laser illumination module provided in this application embodiment, four lenses (such as the first lens 201, the second lens 202, the third lens 205, and the fourth lens 207) and the compound eye lens 204 play a crucial role. They are mainly responsible for controlling the illumination light incident on the surface of the DMD chip 209 (digital micromirror device), including the precise adjustment of the spot size and incident angle. Therefore, when the DMD chip 209 needs to be replaced, for example, from 0.47 inches to 0.39 inches (or other sizes such as 0.65 inches), since the requirements of the incident illumination light differ for different sizes of DMD chips 209, it is usually necessary to redesign each lens and the compound eye lens 204 to ensure that the illumination light can be accurately projected onto the surface of the DMD chip 209 and meet its specific optical performance requirements.

[0075] This application specifically optimizes the design of a compatible laser illumination module for 0.39-inch and 0.47-inch DMD chips 209. As shown in Figure 3, the main improvement is to the relay optical path of the laser illumination module. While maintaining full compatibility between the compound eye lens 204 and the four lenses (such as the first lens 201, the second lens 202, the third lens 205, and the fourth lens 207), an approximately 1.2x zoom function is achieved by adjusting the spacing between the fourth lens 207 and other lenses (such as the third lens 205) and the internal total reflection prism 208. This zoom function can flexibly change the area of ​​the light spot and the incident angle, thereby meeting the different requirements of the 0.39-inch and 0.47-inch DMD chips 209 for the incident illumination light. In short, by precisely adjusting the position of the fourth lens 207, it can be ensured that the illumination light maintains optimal optical performance when projected onto DMD chips 209 of different sizes, including high illuminance uniformity, small light spot size, and precise incident angle.

[0076] The design in this example allows the laser illumination module to be more compatible with both 0.39-inch and 0.47-inch DMD chips 209, reducing dependence on specific DMD chips and improving the versatility and flexibility of the laser illumination module. By controlling the focal length ratio range, a more precise zoom effect is achieved, improving the adaptability and performance of the laser illumination module in different application scenarios. When adjusting the zoom within the focal length ratio range, relatively stable optical performance can be maintained, ensuring that image quality is not affected by zoom operations.

[0077] In some examples of this application, referring to Figures 1 and 2, when the first lens group includes a first lens 201 and a second lens 202, the diffuser 203 is located between the first lens 201 and the second lens 202.

[0078] The main function of the diffuser 203 is to suppress laser speckle, that is, to reduce or eliminate interference patterns caused by the coherence generated by the laser source 100. These patterns may appear as alternating bright and dark spots on the projected image, affecting the visual effect.

[0079] The diffuser 203 is, for example, a vibration diffuser.

[0080] Placing the diffuser 203 between the first lens 201 and the second lens 202 is based on a comprehensive consideration of optical path design and speckle suppression effect. This position ensures that the illumination light emitted from the laser source 100, i.e., the laser light, is focused or collimated to a certain extent before passing through the diffuser 203 for speckle suppression, thereby more effectively reducing the generation of interference patterns.

[0081] In one example, referring to Figures 1 and 2, the first lens group includes a first lens 201 and a second lens 202 spaced apart along the same optical axis. The main function of this lens combination is to shape and adjust the angle of the beam, preparing for subsequent homogenization and projection. The addition of the diffuser 203 not only does not impair this function, but also improves the optical performance of the entire laser illumination module, especially in suppressing speckle.

[0082] By suppressing laser speckle, the uniformity and clarity of the projected image can be significantly improved, reducing visual interference caused by interference patterns. This design enables the laser illumination module of this application to be applicable to a wider range of DMD chips, as speckle suppression is a key factor in improving image quality and is equally important for DMD chips of different sizes.

[0083] In summary, when the first lens group includes a first lens 201 and a second lens 202, the design of placing the diffuser 203 between the first lens 201 and the second lens 202 has significant technical effects in improving image quality, enhancing compatibility, optimizing light efficiency, and simplifying optical path design.

[0084] It should be noted that when only one lens is used in the first lens group, the lens can be either the first lens 201 or the second lens 202.

[0085] For example, the first lens group includes a first lens 201 and a diffuser 203, wherein the diffuser 203 is placed between the light-emitting side of the first lens 201 and the compound eye lens 204.

[0086] For example, the first lens group includes a second lens 202 and a diffuser 203, wherein the diffuser 203 is placed between the laser source 100 and the second lens 202.

[0087] In some examples of this application, the first lens 201, the second lens 202, the third lens 205 and the fourth lens 207 are glass spherical lenses.

[0088] Compared to aspherical lenses, spherical glass lenses are less expensive to manufacture because their processing and testing are relatively simpler. Glass also possesses excellent optical properties and stability, and can withstand high temperatures and pressures, making it suitable for high-power laser projection systems.

[0089] In the laser illumination module provided in the embodiments of this application, all lenses (such as the first lens 201, the second lens 202, the third lens 205, and the fourth lens 207) are spherical. Compared with existing solutions that typically have only one spherical lens and the others are aspherical, the design of this application can significantly reduce production costs.

[0090] In this application, although all lenses are designed to be spherical, high imaging quality and image uniformity can still be achieved through precise optical path layout and lens parameter selection.

[0091] Of course, without considering cost, all lenses in the laser illumination module provided in this application embodiment can also be glass aspherical lenses.

[0092] In some examples of this application, when the DMD chip 209 is 0.39 inches, the F-number of the laser illumination module is F1, and when the DMD chip 209 is 0.47 inches, the F-number of the laser illumination module is F2, then F1 < F2.

[0093] The F-number (also known as the aperture number) is the ratio of the focal length to the entrance pupil diameter in an optical system. It determines the system's light throughput and depth of field. The smaller the F-number, the greater the light throughput and the shallower the depth of field; the larger the F-number, the smaller the light throughput and the deeper the depth of field.

[0094] The DMD chip is a core component in laser projection products, and its size determines the design of the relay section of the illumination module. As the size of the DMD chip increases, in order to maintain the same illumination uniformity and spot size, it is usually necessary to increase the focal length of the relay section, which leads to an increase in the F-number.

[0095] In this application, when the size of the DMD chip 209 is small (e.g., 0.39 inches), a larger luminous flux is required to obtain sufficient brightness and contrast. Therefore, choosing a smaller F-number (F1) can increase the luminous flux and ensure illumination quality. However, when the size of the DMD chip 209 is large (e.g., 0.47 inches), although the luminous flux requirement is relatively low, in order to ensure illumination uniformity and reduce spot distortion, it is necessary to increase the focal length and correspondingly increase the F-number (F2).

[0096] For example, the DMD chip 209 has a size of 0.39 inches and an F1 of 2.0; the DMD chip 209 has a size of 0.47 inches and an F2 of 2.4.

[0097] The laser illumination module provided in this application embodiment has a zoom function, which can be compatible with DMD chips 209 of different sizes by adjusting the focal length of the relay section. The different designs of F1 and F2 ensure that the best illumination effect can be obtained under different DMD chip sizes. By selecting an appropriate F number for DMD chips of different sizes, the best illumination quality and image uniformity can be ensured under any circumstances. A smaller F number (F1) provides a larger luminous flux when the DMD chip size is smaller, which helps to improve the overall luminous efficacy and brightness.

[0098] In some examples of this application, when the DMD chip 209 is 0.39 inches, the effective optical aperture of the fourth lens 207 is D1; ​​when the DMD chip 209 is 0.47 inches, the effective optical aperture of the fourth lens 207 is D2, and D1 = D2.

[0099] By maintaining the same effective optical aperture (D1 = D2) for the fourth lens 207 across different DMD chip sizes, this design enables the laser illumination module to be compatible with DMD chips of different sizes, such as 0.39 inches and 0.47 inches, without the need to replace the lens.

[0100] This compatibility reduces module redesign and manufacturing costs associated with DMD chip replacement. A unified lens design reduces the complexity of production and inventory management. Material and manufacturing costs are saved because there's no need to customize lenses of different apertures for different DMD chip sizes. Designers are also streamlined by not needing to develop multiple lens specifications for different DMD chip sizes.

[0101] Maintaining consistency in the effective optical aperture of the lens helps ensure that the optical performance (such as spot size, incident angle, and relative illumination) of the laser illumination module remains consistent across different DMD chip sizes. This contributes to improving the quality and consistency of the final projected image.

[0102] In some examples of this application, the optical power of the first lens 201, the second lens 202, the third lens 205 and the fourth lens 207 are all positive.

[0103] Lenses with positive optical power have the characteristic of converging light. Therefore, when the optical power of all four lenses in the laser illumination module is positive, they can more effectively converge the light emitted by the laser source 100 and guide it to the DMD chip 209, thereby improving the utilization rate of light and the brightness of the projected image.

[0104] In the laser illumination module provided in this application, four lenses with positive optical power can work together to shape and adjust the angle of the incident illumination light. This is crucial for ensuring that the light is incident on the DMD chip 209 at the appropriate angle and size, which helps to optimize the uniformity and contrast of the projected image.

[0105] A lens combination with positive optical power helps reduce light loss and distortion during transmission, thereby improving the stability and reliability of the entire laser illumination module. This is crucial for ensuring the clarity and stability of the projected image. Furthermore, using a lens combination where all lenses have positive optical power simplifies the design process, as it eliminates the need to consider the complex combinations and corrections between lenses of different optical powers.

[0106] In some examples of this application, referring to Figure 1, the first lens 201 is a convex-concave lens, the second lens 202 is a concave-convex lens, and the third lens 205 and the fourth lens 207 are biconvex lenses.

[0107] The first lens 201 is a convex-concave lens, with one side near the laser source 100 being convex and the other side being concave. The second lens 202 is a concave-convex lens, with one side near the laser source 100 being concave and the other side being convex. The third lens 205 and the fourth lens 207 are both biconvex lenses, meaning both sides are convex.

[0108] The first lens 201 (convex-concave lens): its convex surface is used to converge light rays, while its concave surface may be used to adjust the divergence angle of light rays or to perform aberration correction. This combination helps to effectively shape and pre-control light rays in the initial stage.

[0109] The second lens 202 (concave-convex lens): Its surface design, which is opposite to that of the first lens 201, may be used to further adjust the path and angle of light to achieve more precise beam control.

[0110] The third lens 205 and the fourth lens 207 (biconvex lenses): The biconvex design significantly enhances the ability to converge light, helping to further converge the light after it has been shaped by the first two lenses and guide it to the DMD chip 209. By adjusting the relative position or spacing between the fourth lens 207, the third lens 205, and the internal total internal reflection prism 208, a zoom function can be achieved to a certain extent. The zoom function is particularly important when compatibility with DMD chips of different sizes is required.

[0111] In this example, different lens surface combinations help correct various aberrations, such as spherical aberration, coma, and astigmatism. Through specially designed lens surface shapes and combinations, the sharpness and quality of the projected image can be significantly improved. Using these specific lens surface combinations in this example helps reduce light loss and distortion during transmission, which contributes to improving the stability and reliability of the entire laser illumination module, thereby ensuring the stability and consistency of the projected image.

[0112] In some examples of this application, the compound eye lens 204 is a double-sided compound eye with an incident light angle ≤10° and a thickness ≤5mm.

[0113] The double-sided compound eye design effectively homogenizes and shapes the incident illumination light. The compound eye lens is composed of many small lens units, each of which can make fine adjustments to the light, thereby making the entire light spot more uniform and reducing unevenness in brightness.

[0114] Limiting the incident light angle to ≤10° helps ensure that light enters the compound eye at an appropriate angle, avoiding light loss or distortion caused by excessive angles. This helps maintain light quality and improves the clarity of the projected image. Furthermore, this limitation on the incident light angle also facilitates the optimization of the compound eye lens design.

[0115] The thickness of the compound eye lens 204 is ≤5mm, which helps to reduce the size and weight of the entire optical system, making the laser illumination module more compact and lightweight.

[0116] In some examples of this application, referring to Figures 1 and 2, the first lens 201, the second lens 202 and the third lens 205 are arranged along the first optical axis, and the fourth lens 207 is arranged along the second optical axis, with the first optical axis and the second optical axis forming an angle; the reflector 206 is inclined and is used to project the light emitted from the third lens 205 onto the fourth lens 207.

[0117] In this application, the first lens 201, the second lens 202, and the third lens 205 are arranged along a first optical axis, and the fourth lens 207 is arranged along a second optical axis, which forms a certain angle with the first optical axis. A reflector 206 located between the third lens 205 and the fourth lens 207 is inclined, and its position and function are to reflect the light emitted from the third lens 205 and project it onto the fourth lens 207, thereby achieving the reversal and expansion of the optical path.

[0118] By setting up reflector 206, the optical path was successfully redirected, allowing light rays that originally traveled along the first optical axis to change direction and continue traveling along the second optical axis. This not only saves space but also makes the layout of the optical system more flexible and compact.

[0119] The reflector 206 is tilted to prevent light from directly hitting the edges or corners of the mirror, reducing light loss and distortion caused by mirror damage or contamination. This arrangement also helps improve the stability and reliability of the entire optical system, ensuring stable performance during long-term operation.

[0120] It should be noted that, referring to Figures 1 and 2, the sides of the fourth lens 207 adjacent to the inner total internal reflection prism 208 are, for example, arranged parallel to each other. Of course, in actual production, the sides of the fourth lens 207 adjacent to the inner total internal reflection prism 208 can also form an angle of, for example, within 2°.

[0121] In some examples of this application, the second lens group further includes a fifth lens located between the third lens 205 and the fourth lens 207.

[0122] In this example of the application, a fifth lens can be added to the second lens group. This fifth lens can be designed to be located between the third lens 205 and the fourth lens 207, that is, after light exits from the third lens 205, it can first pass through the fifth lens, and then be reflected by the reflector 206 to the fourth lens 207. The addition of this fifth lens provides more means of optical path control, and can further optimize the shape, size and angle of the light spot to meet the illumination requirements of different DMD chips 209. In addition, in a zoom laser illumination module, the addition of the fifth lens may help to expand the zoom range, enabling the module to be compatible with more types of DMD chips.

[0123] In some examples of this application, the lighting module further includes a laser light source 100 located on the light-incident side of the first mirror group.

[0124] The laser source 100 serves as the light source for the entire laser lighting module, providing illumination for subsequent optical components. The laser source 100 boasts advantages such as high brightness, high color saturation, and long lifespan, significantly improving the luminous efficiency and performance of the lighting module. Due to the good stability of the laser source, the overall system stability of the lighting module is also enhanced. Furthermore, the inclusion of the laser source allows the lighting module to be applied to a wider range of application scenarios.

[0125] Referring to Figures 4 and 5, which show the spot diagrams of the DMD chip 209 at 0.39 inches and 0.47 inches respectively, the RMS (root mean square) spot radius is less than 103 micrometers, which indicates that the light is well focused and the light energy can be used efficiently.

[0126] Figure 6 shows the light trace diagram of the image plane of the laser illumination module according to an embodiment of this application. As can be clearly seen from Figure 6, the laser illumination module can well meet the spot size requirements of the incident light onto the 0.39-inch and 0.47-inch DMD chips 209, thereby achieving compatibility with DMD chips of different sizes.

[0127] Figures 7 and 8 show the relative illuminance diagrams for the 0.47-inch and 0.39-inch laser illumination modules using the DMD chip 209, respectively. Figure 7 shows that the relative illuminance remains almost constant across the entire field of view, close to 1.0, indicating very uniform illumination with no significant unevenness. Figure 8 also shows that the relative illuminance remains almost constant across the entire field of view, close to 1.0, further demonstrating the very uniform illumination within this field of view.

[0128] In one example, the optical parameters of the laser illumination module of this application are designed as shown in Tables 1 and 2 below; Table 1 is the design specification table of the laser illumination module, and Table 2 is the optical parameter table.

[0129] Table 1

[0130] Table 2

[0131] Referring to Table 2, the distance between the center of the fourth lens 207 and the center of the third lens 205 and the center of the internal total reflection prism 208 changes before and after the fourth lens 207 is moved.

[0132] Specifically, surface number 9 in Table 2 shows that after the fourth lens 207 is moved, the distance between its center and the center of the third lens 205 changes by 1 mm. Referring further to Table 1, surface number 11 shows that after the fourth lens 207 is moved, the distance between its center and the internal total internal reflection prism 208 changes by 1 mm. These changes enable the laser illumination module of this application to accommodate both 0.39-inch and 0.47-inch DMD chips.

[0133] According to another embodiment of this application, an optical projection system is provided. Referring to FIG1, the optical projection system includes a laser illumination module and a projection lens 300 as described above, wherein the projection lens 300 is located on the light-emitting side of the internal total reflection prism 208.

[0134] This embodiment provides an optical projection system, which mainly includes two parts: a laser illumination module as described above, and a projection lens 300 located on the light-emitting side of the laser illumination module. The laser illumination module is responsible for generating and controlling the illumination light to meet the illumination requirements of the DMD chip 209 (digital micromirror device), while the projection lens 300 is responsible for magnifying the image light reflected from the DMD chip 209 and projecting it onto a screen.

[0135] The specific structure and working principle of the laser illumination module have been described in detail above. Among them, the design of the relay optical path is particularly critical, as it enables zoom functionality, thereby ensuring compatibility with DMD chips 209 of different sizes, such as 0.39-inch and 0.47-inch chips.

[0136] The projection lens 300 is located on the light-emitting side of the internal total internal reflection prism 208. It is responsible for receiving the image light reflected by the DMD chip 209 and refracted by the internal total internal reflection prism 208, and magnifying it to form a projected image. The specific design and parameter selection of the projection lens 300 will be adjusted according to the actual application scenario and projection requirements.

[0137] Because the laser illumination module has a zoom function and is compatible with DMDs of different sizes, the optical projection system can also adapt to projection chips of different sizes and types, thus improving the system's versatility and flexibility.

[0138] According to yet another embodiment of this application, a smart head-mounted device is provided, the smart head-mounted device including a housing and an optical projection system as described above.

[0139] The specific implementation of the smart head-mounted device in this application can refer to the various embodiments of the laser illumination module described above. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0140] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0141] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A laser illumination module, characterized in that, include: The first lens group includes at least one of a first lens (201) and a second lens (202), and a diffuser (203); The compound eye lens (204) is located on the light-emitting side of the first lens group; The second lens group includes a third lens (205) and a fourth lens (207); A reflector (206) is located in the optical path between the third lens (205) and the fourth lens (207) to change the direction of the optical path; An internal total internal reflection prism (208) is located on the light-emitting side of the fourth lens (207); The DMD chip (209) is disposed adjacent to the internal total reflection prism (208); The fourth lens (207) can move along its optical axis to change its distance from the third lens (205) and the internal total reflection prism (208), thereby achieving zoom. The DMD chip (209) receives the zoomed illumination light, enabling the laser illumination module to be matched with DMD chips (209) of different sizes.

2. The laser illumination module according to claim 1, characterized in that, The laser illumination module satisfies: 1.2≤|f1 / f2|≤1.5; where f1 and f2 are the focal lengths of the laser illumination module corresponding to the DMD chip (209) being 0.39 inches and 0.47 inches, respectively.

3. The laser illumination module according to claim 2, characterized in that, When the first lens group includes a first lens (201) and a second lens (202), the diffuser (203) is located between the first lens (201) and the second lens (202).

4. The laser illumination module according to claim 3, characterized in that, The first lens (201), the second lens (202), the third lens (205) and the fourth lens (207) are glass spherical lenses.

5. The laser illumination module according to claim 4, characterized in that, When the DMD chip (209) is 0.39 inches, the F number of the laser illumination module is F1; when the DMD chip (209) is 0.47 inches, the F number of the laser illumination module is F2. Therefore, F1 < F2.

6. The laser illumination module according to claim 4, characterized in that, When the DMD chip (209) is 0.39 inches, the effective optical aperture of the fourth lens (207) is D1, and when the DMD chip (209) is 0.47 inches, the effective optical aperture of the fourth lens (207) is D2, and D1 = D2.

7. The laser illumination module according to claim 4, characterized in that, The optical power of the first lens (201), the second lens (202), the third lens (205) and the fourth lens (207) is positive.

8. The laser illumination module according to claim 7, characterized in that, The first lens (201) is a convex-concave lens, the second lens (202) is a concave-convex lens, and the third lens (205) and the fourth lens (207) are biconvex lenses.

9. The lighting module according to claim 4, characterized in that, The compound eye lens (204) is a double-sided compound eye with an incident light angle ≤10° and a thickness ≤5mm.

10. The laser illumination module according to claim 4, characterized in that, The first lens (201), the second lens (202) and the third lens (205) are arranged along the first optical axis, and the fourth lens (207) is arranged along the second optical axis. The first optical axis and the second optical axis form an angle. The reflector (206) is tilted to project the light emitted from the third lens (205) onto the fourth lens (207).

11. The laser illumination module according to claim 4, characterized in that, The second lens group also includes a fifth lens, which is located between the third lens (205) and the fourth lens (207).

12. The laser illumination module according to any one of claims 1-11, characterized in that, The lighting module also includes a laser light source (100) located on the light-incident side of the first mirror group.

13. An optical projection system, characterized in that, include: The laser illumination module as described in any one of claims 1-12; and A projection lens (300) is located on the light-emitting side of the internal total reflection prism (208).

14. A smart head-mounted device, characterized in that, include: shell; and The optical projection system as described in claim 13.

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