Optical-mechanical module and augmented reality device

Abstract

The application provides an optical-mechanical module and an augmented reality device, and belongs to the technical field of optical display devices. The optical-mechanical module comprises a laser light source for providing laser light; a spatial light modulator for modulating the laser light and forming imaging light, the laser light emitted by the laser light source being incident on the spatial light modulator at a first incident angle; a total internal reflection prism, the imaging light emitted by the spatial light modulator being incident on a first reflecting surface of the total internal reflection prism at a second incident angle and being incident on a first mirror surface after at least one total reflection, the surface of the first mirror surface being provided with a polarization beam splitter film; and a reflecting curved surface, the surface of the reflecting curved surface being provided with a semi-transparent semi-reflective film and being used for reflecting the imaging light reflected by the first mirror surface into a human eye. The laser optical expansion is small, the imaging light emitted by the spatial light modulator has a small beam angle, the optical path lateral length of the imaging light is folded by means of total reflection, the volume of the optical-mechanical module is reduced, and the miniaturization and thinning of the augmented reality device are facilitated.

Description

Technical Field

[0001] This application belongs to the field of optical display equipment technology, and more specifically, relates to an optical engine module and an augmented reality device. Background Technology

[0002] Augmented reality (AR) devices are widely used in industrial inspection, medical imaging, and autonomous driving, with the optomechanical module being a core component. Micro-organic light-emitting diodes (micro-OLEDs) are currently widely used as display chips in optomechanical modules due to their high resolution, fast response, and self-emissive characteristics. However, the imaging light produced by micro-OLEDs is unpolarized, requiring a polarizer, which increases the overall structural size and hinders the miniaturization of AR devices. Summary of the Invention

[0003] The purpose of this application is to provide an optical engine module and an augmented reality device to solve the technical problem that the optical engine module is large in size and difficult to miniaturize in the prior art.

[0004] To achieve the above objectives, the technical solution adopted in this application is: an optomechanical module, comprising:

[0005] Laser source, used to provide laser beams;

[0006] A spatial light modulator is used to modulate the laser beam and form an imaging beam, wherein the laser beam emitted by the laser source is incident on the spatial light modulator at a first incident angle;

[0007] A total internal reflection prism, wherein the imaging light emitted from the spatial light modulator is incident on the first reflecting surface of the total internal reflection prism at a second incident angle, and after at least one total internal reflection, is incident on the first mirror surface, the surface of the first mirror surface having a polarizing beam splitting film;

[0008] A reflective surface, the surface of which has a semi-transparent and semi-reflective film, is used to reflect the imaging light reflected by the first mirror into the human eye.

[0009] Optionally, the first incident angle is θ1, θ1=[arctan(1 / F#)]*180 / π, where F# is the F number of the optical system between the laser source (10) and the spatial light modulator (20);

[0010] The second incident angle is θ2, θ2-θ1≥θc, where θc is the critical angle for total internal reflection of the total internal reflection prism (30).

[0011] Optionally, the imaging light emitted from the spatial light modulator undergoes at least two total internal reflections within the total internal reflection prism.

[0012] Optionally, the optomechanical module further includes a cemented prism and a compensating lens, wherein the cemented surface of the cemented prism forms the first mirror surface, and the compensating lens is disposed on the curved side of the reflective surface.

[0013] Optionally, the total internal reflection prism and the cemented prism are an integral structure.

[0014] Optionally, the first mirror is a plane mirror, the plane mirror and the reflecting surface form a hollow mirror, and the polarizing light-emitting film is disposed on the side of the plane mirror facing the reflecting surface.

[0015] Optionally, the optomechanical module further includes a first lens, which is disposed between the first mirror and the total internal reflection prism.

[0016] Optionally, a quarter-wave plate is provided between the first mirror surface and the reflecting surface.

[0017] Optionally, the laser source includes a red laser source, a green laser source, a blue laser source, a diffractive optical element, and a beam combiner. A diffractive optical element is provided corresponding to each of the red, green, and blue laser sources. The beam combiner is used to combine the three-color lasers passing through the diffractive optical element into a white laser. A half-wave plate is provided between the red laser source and the corresponding diffractive optical element.

[0018] Optionally, the optomechanical module further includes a second lens located between the laser source and the total internal reflection prism, and the spatial light modulator is located at the focal plane of the second lens.

[0019] Optionally, the spatial light modulator is a DMD chip;

[0020] And / or, the surface curvature of the reflective surface is the same as the surface curvature of the human eye.

[0021] This application also provides an augmented reality device, which includes:

[0022] shell;

[0023] The optical engine module as described above is mounted on the housing.

[0024] The beneficial effects of the optical engine module and augmented reality device provided in this application are as follows: Compared with micro-OLED chips as display chips, the optical engine module provided in this application uses a laser light source and a spatial light modulator to form imaging light, which can improve the brightness and color gamut of the image, and has a longer service life. The laser optical expansion is small, and the imaging light emitted from the spatial light modulator has a small beam angle. The optical lenses in the optical engine module can be made thinner. Moreover, the imaging light is guided to the first mirror by a total internal reflection prism. By using the total internal reflection prism to fold the lateral length of the optical path of the imaging light, the volume of the optical engine module is further reduced. This allows the optical module to achieve a larger field of view with a thinner and lighter volume, improves the user's viewing experience, and helps to realize the miniaturization and thinning of augmented reality devices. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art 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.

[0026] Figure 1 This is one of the structural schematic diagrams of the optomechanical module provided in the embodiments of this application;

[0027] Figure 2 for Figure 1 The diagram shown is a structural schematic of the optomechanical module when the laser source is a three-color laser source;

[0028] Figure 3 for Figure 1 The diagram shows the optical path of the optomechanical module.

[0029] Figure 4 To use micro-OLED as the display chip and Figure 1 The diagram shows the optical path of the optomechanical module formed by the prism structure shown.

[0030] Figure 5 This is a second schematic diagram of the structure of the optomechanical module provided in the embodiments of this application;

[0031] Figure 6 for Figure 5 The diagram shown is a structural schematic of the optomechanical module when the laser source is a three-color laser source;

[0032] Figure 7 for Figure 6 The diagram shown illustrates the structure of the optomechanical module when there are large assembly errors in the total internal reflection prism and the cemented prism.

[0033] Figure 8 This is the third schematic diagram of the structure of the optomechanical module provided in the embodiments of this application;

[0034] Figure 9 for Figure 8 The diagram shown is a structural schematic of the optomechanical module when the laser source is a three-color laser source;

[0035] Figure 10 This is the fourth schematic diagram of the structure of the optomechanical module provided in the embodiments of this application;

[0036] Figure 11 for Figure 10 The diagram shown is a structural schematic of the optomechanical module when the laser source is a three-color laser source;

[0037] Figure 12 This is a schematic diagram of the principle of the diffractive optical source element in the optomechanical module provided in the embodiments of this application.

[0038] The following are the labeling elements in the figure:

[0039] 10. Laser source; 11. Green laser source; 12. Blue laser source; 13. Red laser source; 14. Diffractive optical element; 15. Mirror; 16. First dichroic mirror; 17. Second dichroic mirror; 18. Half-wave plate; 20. Spatial light modulator; 30. Total internal reflection prism; 40. Reflective surface; 41. Semi-transparent and semi-reflective coating; 42. Quarter-wave plate; 50. First mirror; 51. Cemented prism; 52. Plane mirror; 60. Compensating lens; 70. First lens; 80. Second lens; 100. Natural light; 201. Micro-OLED chip; 202. Polarizer. Detailed Implementation

[0040] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0041] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0042] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0044] Please refer to the following: Figures 1 to 11 The optomechanical module provided in this application embodiment will now be described. The optomechanical module includes a laser source 10, a spatial light modulator 20, a total internal reflection prism 30, a first mirror 50, and a reflective surface 40. The laser source 10 is used to provide laser light for illumination. The spatial light modulator 20 is used to modulate the laser light and form an imaging light. The laser light emitted by the laser source is incident on the spatial light modulator 20 at a first incident angle θ1. The total internal reflection prism 30 is used to guide the imaging light to the first mirror 50. The imaging light emitted from the spatial light modulator 20 is incident on the first reflective surface of the total internal reflection prism 30 at a second incident angle θ2, and after at least one total internal reflection, it is incident on the first mirror 50. The surface of the first mirror 50 has a polarizing beam splitter, and the surface of the reflective surface 40 has a semi-transparent and semi-reflective film 41, which is used to reflect the imaging light reflected from the first mirror 50 to the human eye.

[0045] Before the laser light provided by the laser source 10 illuminates the spatial light modulator 20, it undergoes homogenization and shaping processes to ensure that the intensity and shape of the target light spot formed on the spatial light modulator 20 meet the requirements. Compared to the micro-OLED chip 201 as a display chip, the optical extension of the laser source 10's optomechanical module is small, and its brightness is high, which can improve the brightness and color gamut of the screen. Optical extension is an important physical quantity that measures the light energy transmission capability in an optical system. It is related to the emitting area and emission solid angle of the light source and is expressed by the formula U = A·Ω, where U is the optical extension, A is the emitting area of ​​the light source, and Ω is the emission solid angle. Lasers are generated through stimulated emission, and their emission mechanism allows them to be generated in a relatively small area, resulting in a small emitting area. Moreover, lasers have high directionality, and their beam divergence angle is very small, which means that the laser light propagates almost along a specific direction, resulting in a very small emission solid angle. Therefore, according to the formula, the optical extension of the laser source is small. In the optomechanical module that uses the micro-OLED chip 201 as the display chip, the optical extension is close to that of a Lambertian volume, emitting light in all directions, and the emission solid angle is close to 4π spherical degrees; while the divergence angle of the laser beam is only about π / 90 milliradians.

[0046] Please refer to the following: Figure 3 and Figure 4 , Figure 3 The laser source 10 provided in the embodiments of this application serves as the light source. Figure 4 Instead of using a traditional micro-OLED chip 201 as the display chip, a polarizer 202 is placed at the light emission point of the micro-OLED chip 201 to convert the unpolarized light emitted by the micro-OLED chip 201 into linearly polarized light. (Comparison) Figure 3 and Figure 4 It is evident that, given the same size of the spatial light modulator 20 and the micro-OLED chip 201, the beam angle emitted from the spatial light modulator 20 is smaller than that emitted from the micro-OLED chip 201. This results in a narrower beam as it propagates from the spatial light modulator 20 to the human eye. Therefore, the lenses in the optomechanical module provided in this embodiment are more flexible compared to... Figure 4 It can be made even thinner. Specifically, the laser beam... Figure 3 The cross-section of the light spot at point A has a long side dimension of 8–18 mm and a short side dimension of 5–10 mm, with the long and short sides of the light spot corresponding to the long and short sides of the spatial light modulator 20. To achieve the same light spot cross-section, Figure 3 The distance L1 from the exit surface of the prism to the reflecting surface 40 is 5.5–11 mm. Figure 4 The distance L2 from the exit surface of the prism to the reflecting surface 40 is 8–16 mm.

[0047] See Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 10 and Figure 11 The total internal reflection prism 30 is a right-angled prism, shaped like an isosceles right triangle. A laser beam enters the prism 30 from its inclined surface, refracts, and exits through one right-angled surface, illuminating the spatial light modulator 20. The imaging ray formed by the spatial light modulator 20 enters the prism 30 from this right-angled surface, undergoes total internal reflection on the inclined surface, and exits through another right-angled surface. Specifically, the angle of incidence of the imaging ray on the inclined surface of the prism 30 is greater than the critical angle, causing total internal reflection at the surface. The imaging ray exits the right-angled surface of the prism 30 and then enters the first mirror 50. It should be noted that the imaging ray exiting the right-angled surface of the prism 30 can directly enter the first mirror 50, or it can pass through other optical elements before entering the first mirror 50.

[0048] The first mirror surface 50 is a reflective surface of a plane mirror or prism. In the case where the first mirror surface 50 is a plane mirror, refer to... Figure 10 and Figure 11 A plane mirror is connected to a reflecting surface 40 to form a hollow mirror. Natural light 100 passes through the reflecting surface 40 and becomes polarized light, then enters the human eye after passing through the first mirror 50 with a semi-transparent and semi-reflective coating 41. In the case where the first mirror 50 is a reflective surface of a prism, see [reference needed]. Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 8 and Figure 9 A compensating lens 60 can be set on the curved side of the reflective surface 40 so that natural light 100 can smoothly enter the human eye.

[0049] Optionally, the laser beam, after being refracted by the total internal reflection prism 30, is incident on the spatial light modulator 20. The total internal reflection prism 30 separates the incident and outgoing light on the spatial light modulator 20. Other methods may also be used to separate the incident and outgoing light before the laser beam hits the spatial light modulator 20; this application does not specifically limit this. The imaging light beam formed by the spatial light modulator 20 enters the total internal reflection prism 30 and undergoes total internal reflection inside, reducing the direction of the imaging light beam and folding the optical path. Traditional VR devices require a long optical path to focus the image, making the devices relatively thick and heavy. This application uses the total internal reflection prism 30 to cause the imaging light beam to undergo total internal reflection within the prism 30, folding the optical path and preventing light leakage, thereby improving contrast. (See also...) Figure 1 and Figure 2The light beam from the spatial light modulator 20 undergoes total internal reflection in the total internal reflection prism 30 and then shines on the first mirror 50, resulting in at least two total reflections. This allows the optical path to be folded, further reducing the thickness of the lenses in the optical-mechanical module under the same optical path length.

[0050] Compared to the traditional micro-OLED chip 201 used as the display chip, the optical engine module provided in this application uses a laser light source 10 to provide a laser light source. The optical extension is small, and the imaging light emitted from the spatial light modulator 20 has a small beam angle. The optical lenses in the optical engine module can be made thinner. Moreover, the imaging light is guided to the first mirror 50 by the total internal reflection prism 30. By utilizing the lateral length of the optical path of the imaging light folded by the internal reflection within the total internal reflection prism 30, the volume of the optical engine module is further reduced. Thus, the optical module can achieve a larger field of view with a thinner and lighter volume, improving the user's viewing experience.

[0051] See Figure 1 In the optomechanical module, the laser light emitted from the laser source 10 is incident on the spatial light modulator 20 at a first incident angle θ1, and the imaging light emitted from the spatial light modulator 20 is incident on the first reflecting surface of the total internal reflection prism 30 at a second incident angle θ2. Here, θ1 = [arctan(1 / F#)]*180 / π, where F# is the F-number of the optical system between the laser source 10 and the spatial light modulator 20.

[0052] To ensure total internal reflection occurs on the first reflecting surface of the total internal reflection prism 30, θ2-θ1≥θc, where θc is the critical angle for total internal reflection of the imaging ray entering the total internal reflection prism 30 from air. θc=[arcsin(1 / n)]*180 / π, where n is the refractive index of the total internal reflection prism 30.

[0053] See Figure 1 The angle θ3 of the total internal reflection prism is θ2, from which we can obtain that θ3 ≥ [arctan(1 / F#) + arcsin(1 / n)] * 180 / π.

[0054] The imaging light emitted from the spatial light modulator 20 undergoes at least two total internal reflections within the total internal reflection prism 30. With the total internal reflection superimposed on the first mirror 50, the imaging light emitted from the spatial light modulator 20 undergoes at least three total internal reflections before entering the reflecting surface 40.

[0055] For example, the imaging light emitted from the spatial light modulator 20 undergoes two or three total internal reflections within the total internal reflection prism 30. (See also...) Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 8 and Figure 9The imaging light emitted from the spatial light modulator 20 undergoes two total internal reflections within the total internal reflection prism 30, and then a third total internal reflection within the first mirror 50; Figure 4 In the conventional scheme shown, the light beam undergoes only two total internal reflections within the prism. Therefore, the optical-mechanical module provided in this application can further fold the optical path, and the thickness of the optical-mechanical module can be reduced under the same optical path, which helps to realize the miniaturization and thinning of augmented reality devices.

[0056] See Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 8 and Figure 9 The optomechanical module also includes a cemented prism 51 and a compensating lens 60. The cemented surface of the cemented prism 51 forms a first mirror surface 50. The compensating lens 60 is disposed on the curved side of the reflecting surface 40.

[0057] The polarizing beam splitter is disposed on the bonding surface of the cemented prism 51. (See reference...) Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 8 and Figure 9 The imaging light rays emitted from the total internal reflection prism 30 enter the cemented prism 51 and undergo total internal reflection at the interface between the cemented prism 51 and the air. Specifically, at the interface between the cemented prism 51 and the air, the angle of incidence of the imaging light rays is greater than the critical angle, therefore the imaging light rays undergo total internal reflection and are reflected to the cemented surface of the cemented prism 51. It should be noted that the imaging light rays undergo at least one total internal reflection within the cemented prism 51, thereby further folding the optical path and reducing the size of the optomechanical module.

[0058] See Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 8 and Figure 9 The compensation lens 60 is positioned on the curved side of the reflective surface 40. Natural light 100 passes sequentially through the compensation lens 60, the reflective surface 40, and the cemented prism 51 before entering the human eye. By setting the compensation lens 60, the thickness of the lens is made uniform along the path of natural light 100 entering the human eye, thus avoiding distortion of the true image.

[0059] The prism surface through which the imaging light rays are transmitted from the total internal reflection prism 30 is designated as the first prism surface, and the prism surface through which the imaging light rays enter the cemented prism 51 is designated as the second prism surface. In an optional embodiment, both the first and second prism surfaces are planar. See also... Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 8and Figure 9 The imaging light rays, after being transmitted from the first prism surface, propagate through the air and illuminate the second prism surface. They then enter the cemented prism 51 via transmission through the second prism surface, where total internal reflection occurs. In another optional embodiment, both the first and second prism surfaces convex outwards, forming convex surfaces. The distance between the first and second prism surfaces is set according to actual needs, ensuring that the angle of incidence formed by the imaging light rays entering from the second prism surface at the interface between the cemented prism 51 and the air is greater than the critical angle, thus enabling total internal reflection.

[0060] See Figure 7 Significant assembly errors may occur during the assembly of the total internal reflection prism 30 and the cemented prism 51, affecting the display quality of the virtual image. To avoid the impact of these errors, the total internal reflection prism 30 and the cemented prism 51 are integrated into a single structure. (See reference...) Figure 8 and Figure 9 The cemented prism 51 and the total internal reflection prism 30 are an integrated prism. The laser light emitted by the laser source 10 is transmitted through the integrated prism and then shines on the spatial light modulator 20. The imaging light emitted by the spatial light modulator 20 enters the integrated prism and undergoes multiple total internal reflections within the integrated prism, and is reflected at the first mirror surface 50 formed by the cemented surface.

[0061] The optomechanical module provided in this application embodiment integrates the total internal reflection prism 30 and the cemented prism 51 into a single structure, reducing the number of lenses in the optomechanical module and thus reducing the introduction of system tolerances. Under the same system tolerance requirements, the integrated design of the cemented prism 51 and the total internal reflection prism 30, compared to separate installations, reduces the precision requirements for the integrated prism, thereby reducing manufacturing difficulty.

[0062] See Figure 10 and Figure 11 In another embodiment of this application, the first mirror 50 is a plane mirror 52, which forms a hollow mirror with the reflecting surface 40. Compared with the cemented prism 51, this reduces the weight of the optomechanical module. A polarizing light-emitting film is disposed on the side of the plane mirror 52 facing the reflecting surface 40.

[0063] If the imaging light rays from the total internal reflection prism 30 are directly reflected by the first mirror 50 and enter the human eye, aberrations may occur. Therefore, refer to... Figure 10 and Figure 11 The optomechanical module also includes a first lens 70, which is disposed between the first mirror 50 and the total internal reflection prism 30. The ultraviolet light emitted by the laser source 10 passes through the total internal reflection prism 30, is focused by the first lens 70, and then incident on the first mirror 50.

[0064] A quarter-wave plate 42 is provided between the first mirror surface 50 and the reflecting surface 40. The imaging light reflected by the first mirror surface 50 is projected onto the reflecting surface 40 after passing through the quarter-wave plate 42. After being reflected by the reflecting surface 40, it is adjusted to the polarization direction again by the quarter-wave plate 42 and passes through the polarizing beam splitter to enter the human eye.

[0065] A quarter-wave plate 42 is disposed in a film-like form on the side of the reflecting surface 40 facing the first mirror surface 50. For example... Figures 1 to 11 As shown, one side of the reflective surface 40 is convex, and the side facing the first mirror 50 is flat; a quarter-wave plate 42 is disposed on the flat side of the reflective surface 40. The imaging light rays from the total internal reflection prism 30 are projected onto the first mirror 50. After reflection by the first mirror 50, they first pass through the quarter-wave plate 42, and then are reflected again by the reflective surface 40, which has a semi-transparent and semi-reflective coating 41. The imaging light rays reflected by the reflective surface 40 pass through the quarter-wave plate 42 again, changing from S-polarization to P-polarization, thus allowing transmission through the first mirror 50 with the polarizing beam splitter, and entering the human eye, enabling the viewer to see the virtual image. (See reference...) Figures 1 to 11 Natural light 100 enters the human eye through the reflective surface 40 and the first mirror 50.

[0066] In one embodiment of this application, see reference Figure 2 , Figure 6 , Figure 9 and Figure 11 The laser source 10 includes a red laser source 13, a green laser source 11, a blue laser source 12, a diffractive optical element 14, and a beam combiner. A diffractive optical element 14 is provided for each of the red laser source 13, the green laser source 11, and the blue laser source 12. The beam combiner is used to combine the three colors of laser light passing through the diffractive optical element 14 into a white laser.

[0067] Before designing the diffractive optical element (DOE) 14, several key input parameters need to be defined. Firstly, the incident laser has several important physical characteristics, including wavelength and intensity distribution. Wavelength is a fundamental and crucial property of the incident laser; different wavelengths determine the laser's propagation characteristics in the medium and its interaction with matter. Intensity distribution describes the variation in laser intensity at different locations in space, reflecting the spatial distribution characteristics of laser energy. These parameters collectively constitute the basic information of the incident laser and are the important foundation for subsequent calculations and design of the diffractive optical element 14. Secondly, the target laser spot also has a series of specific parameter requirements. The shape of the target laser spot is diverse, including various geometric shapes such as circles, squares, and ellipses, with different application scenarios having different requirements for spot shape. Uniformity describes the degree of consistency in the intensity distribution within the laser spot. In many applications with high requirements for intensity uniformity, such as photolithography and laser displays, uniformity is a key performance indicator.

[0068] Once the wavelength and intensity distribution of the incident laser, as well as the shape, size, and uniformity of the target spot, are determined, a series of mature algorithms can be used to calculate the phase φ of the diffractive optical element 14. The GS algorithm (Gerchberg-Saxton algorithm) is a classic and widely used iterative algorithm. Based on the Fourier transform principle, this algorithm iterates between the object plane and the image plane, gradually adjusting the phase distribution to make the calculated spot characteristics approximate the parameter requirements of the target spot. The YG algorithm (Yang-Gu algorithm) is an improved and optimized version of the GS algorithm. It has advantages in convergence speed and computational accuracy, and can more efficiently calculate the required DOE phase φ. Due to the periodicity of phase, the phase of the diffractive optical element 14 also exhibits a periodic variation. This periodicity allows the DOE phase to be compressed into the range [0, 2π]. This not only simplifies subsequent processing and analysis but also theoretically provides a complete description of the phase characteristics of the diffractive optical element 14.

[0069] However, a real challenge arises in the actual manufacturing process. Current processing technologies and processes have limitations, making it impossible to directly fabricate optical devices with continuous phase. This is because continuous phase optical devices require extremely high processing precision and techniques, which existing equipment and technologies struggle to achieve. Therefore, see [reference needed]. Figure 12The phase φ of the DOE is transformed into a stepped microstructure with different heights. By discretizing the continuous phase distribution into a series of steps with different heights, the height difference of the steps is used to represent the change of the continuous phase. This stepped microstructure is relatively easy to manufacture. Through micro-nano fabrication techniques such as photolithography and etching, these steps can be precisely fabricated on the surface of optical materials, thereby realizing the function of the diffractive optical element 14.

[0070] In summary, the principle of the diffractive optical element 14 involves a series of complex and rigorous processes, from determining the input parameters, calculating the phase using algorithms, and compressing the phase, to finally transforming it into a processable step-like microstructure. Each step is closely interconnected, working together to ensure that the diffractive optical element 14 can achieve the expected optical function. By setting the diffractive optical element 14 to adjust the wavelengths and divergence angles of the red, blue, and green lasers, the three-color beams are shaped into beams matching the effective region of the spatial light modulator 20, and a square light spot with uniform intensity can be formed. (See also...) Figure 12 The three-color laser light is shaped into a rectangular spot after passing through the diffraction optical element 14.

[0071] In an optional embodiment, see [reference] Figure 2 , Figure 6 , Figure 9 and Figure 11The beam combiner includes a reflector 15, a first dichroic mirror 16, and a second dichroic mirror 17. The reflector 15, the first dichroic mirror 16, and the second dichroic mirror 17 are stacked at a specific angle. The reflector 15 achieves total internal reflection, while the first dichroic mirror 16 and the second dichroic mirror 17 can reflect one path of light and transmit other light. A red laser source 13, a green laser source 11, and a blue laser source 12 are respectively positioned corresponding to the reflector 15, the first dichroic mirror 16, and the second dichroic mirror 17. This application does not specifically limit the correspondence between the three light sources (red laser source 13, blue laser source 12, and green laser source 11) and the reflector 15, the first dichroic mirror 16, and the second dichroic mirror 17, as long as the green, blue, and red light can be combined to form white light using the reflector 15, the first dichroic mirror 16, and the second dichroic mirror 17. For example, the green laser emitted by the green laser source 11 enters the main optical path after being reflected by the reflector 15. The first dichroic mirror 16 reflects blue light and transmits green light. Blue laser light emitted from the blue laser source 12 is reflected by the first dichroic mirror 16 and enters the main optical path. Green light is transmitted through the first dichroic mirror 16 and then incident on the second dichroic mirror 17. The second dichroic mirror 17 reflects red light and transmits both blue and green light. Red laser light emitted from the red laser source 13 is reflected by the second dichroic mirror 17 and enters the main optical path. Green and blue light are transmitted through the second dichroic mirror 17 and then combined with the red light to form white light. Alternatively, the blue laser source can be paired with the reflector 15, the green laser source with the first dichroic mirror 16, and the red laser source 13 with the second dichroic mirror 17. Accordingly, the first dichroic mirror 16 reflects green light and transmits blue light, and the second dichroic mirror 17 reflects red light and transmits both blue and green light.

[0072] In another optional embodiment, the beam combiner includes a first polarizing beam splitter, a second polarizing beam splitter, and a half-wave plate. Green light emitted from the green laser source is adjusted to P-polarization and passes directly through the first polarizing beam splitter. Red light emitted from the red laser source is adjusted to S-polarization and, after reflection by the first polarizing beam splitter, becomes coaxial with the green light. Blue light emitted from the blue laser source is rotated to S-polarization by the half-wave plate, and, after reflection by the second polarizing beam splitter, merges with the green and red light to form white light.

[0073] In another embodiment of this application, see [reference] Figure 6 , Figure 9 and Figure 11A half-wave plate 18 is disposed between the red laser source 13 and the corresponding diffractive optical element 14. By distributing the half-wave plate 18 between the red laser source 13 and the corresponding diffractive optical element 14, the red laser can be adjusted from P-polarization to S-polarization, thereby ensuring that the red, blue, and green lasers are all S-polarized, thus matching the polarization direction of the laser light entering the spatial light modulator 20 with the spatial light modulator 20. Alternatively, two quarter-wave plates 42 or other modules can be used between the red laser source 13 and the corresponding diffractive optical element to adjust the polarization direction of the red laser.

[0074] A half-wave plate 18 is placed between the red laser source 13 and the corresponding diffractive optical element 14, so that the red laser undergoes polarization direction conversion before being combined with the blue and green lasers. This can make the polarization direction conversion efficiency of the parallel light emitted from the laser source 10 higher, thereby making the laser light reaching the spatial light modulator 20 more matched with the spatial light modulator 20.

[0075] Since the light emitted directly from the micro-OLED chip 201 is partially polarized, not linearly polarized, a polarizer 202 needs to be installed at the light emission point of the micro-OLED chip 201 to ensure that the light emitted from the micro-OLED chip 201 is reflected as S-polarized light and transmitted as P-polarized light at the polarization beam splitter on the surface of the first mirror 50. The polarizer 202 converts the light emitted from the micro-OLED chip 201 into linearly polarized light, a process that results in a 30-50% efficiency loss. For the three-color laser source provided in this application, the emitted laser light itself is linearly polarized. Only a half-wave plate 18 is needed to adjust the red laser to the same linear polarization state as the blue and green lasers, achieving a conversion efficiency of over 97%. Therefore, this application uses a three-color laser, a total internal reflection prism 30, and a cemented prism 51, which can improve the overall optical efficiency of the optomechanical module.

[0076] In another embodiment of this application, the optomechanical module further includes a second lens 80, which is located between the laser source 10 and the total internal reflection prism 30, and the spatial light modulator 20 is located at the focal plane of the second lens 80.

[0077] See Figure 6 , Figure 9 and Figure 11 The red laser source 13, blue laser source 12, and green laser source 11 converge after passing through the diffractive optical element 14 to form a white laser. Before entering the total internal reflection prism 30, the white laser light passes through the second lens 80 to converge. The laser light transmitted through the second lens 80 is refracted by the total internal reflection prism 30 and then projected onto the spatial light modulator 20.

[0078] Optionally, the spatial light modulator 20 is a digital micromirror device (DMD) or a liquid crystal on silicon (LCOS) chip to improve the contrast of the image.

[0079] Taking the spatial light modulator 20 as an example of a DMD, please refer to... Figure 1 , Figure 2 , Figure 5 , Figure 6 , Figure 8 and Figure 9 The laser light provided by the laser source 10 illuminates the DMD, generating an imaging beam. Total internal reflection occurs when the angle of incidence of the imaging beam at the interface between the total internal reflection prism 30 and air is greater than the critical angle. The imaging beam transmitted from the total internal reflection prism 30 is incident on the cemented prism 51. Since the angle of incidence at the interface between the cemented prism 51 and air is greater than the critical angle, total internal reflection occurs, and the beam is reflected onto the cemented surface of the cemented prism 51. The cemented surface of the cemented prism 51 is coated with a polarizing beam-splitting film, which transmits P-polarized light and reflects S-polarized light. The imaging beam is S-polarized and is reflected by the polarizing beam-splitting film, exiting the cemented prism 51. The reflected imaging beam first passes through a quarter-wave plate 42, then is reflected again on the reflective surface 40 coated with a semi-transparent, semi-reflective film 41, and then passes through another quarter-wave plate 42. Thus, the imaging beam changes from S-polarized to P-polarized after passing through two quarter-wave plates 42. P-polarized imaging light is transmitted through the cemented surface of the cemented prism 51 and enters the pupil of the human eye, allowing the user to see the image displayed on the DMD.

[0080] See Figure 10 and Figure 11The first mirror 50 is a plane mirror 52, which is connected to the reflecting surface 40 to form a hollow mirror for weight reduction. The imaging light reflected from the spatial light modulator 20 forms an incident angle at the interface between the total internal reflection prism 30 and air that is greater than the critical angle of the total internal reflection prism 30, thus causing total internal reflection. After total internal reflection, the imaging light exits the total internal reflection prism 30 and enters the first lens 70. The imaging light emitted from the first lens 70 passes through the plane mirror 52 with a polarizing beam splitter. The polarizing beam splitter reflects S-polarized light and transmits P-polarized light, so the imaging light is now S-polarized and is reflected at the plane mirror 52. The reflected imaging light first passes through a quarter-wave plate 42, and then undergoes partial reflection at the reflecting surface 40 coated with a semi-transparent and semi-reflective film 41. The reflected light then passes through another quarter-wave plate 42, converting from S-polarized light to P-polarized light. At this point, the P-polarized light is transmitted through the plane mirror 52 with the polarizing beam splitter, imaging the DMD image onto the pupil of the human eye. Meanwhile, real images of nature are projected onto the human eye after passing through a reflective surface 40 with a semi-transparent and semi-reflective film 41 and a plane mirror 52 with a polarizing beam-splitting film.

[0081] The laser source 10 includes a red laser source 13, a blue laser source 12, a green laser source 11, and a diffractive optical element 14. The diffractive optical element 14 is used to shape and homogenize the three-color laser beams. The green laser source 11, blue laser source 12, and red laser source 13 are arranged sequentially. A dichroic filter that reflects red light and transmits blue and green light is set corresponding to the red laser source 13; a dichroic filter that reflects blue light and transmits green light is set corresponding to the blue laser source; and a reflector 15 that reflects green light is set corresponding to the green laser source 11. The three-color laser beams emitted by the red laser source 13, blue laser source 12, and green laser source 11 are combined into a white laser beam by the diffractive optical element 14 with the help of the two dichroic filters and the reflector 15. The DMD is set near the focal plane of the second lens 80. The diffractive optical element 14, in conjunction with the second lens 80, shapes the three-color beams into a rectangular spot with uniform intensity distribution that matches the effective area of ​​the DMD. Since red laser light is P-polarized and blue and green laser light is S-polarized, a half-wave plate 18 is added between the red laser light source 13 and the corresponding optical diffraction element to convert the red laser light from P-polarized light to S-polarized light, so that all imaging light rays can be reflected on the cemented surface of the cemented prism 51.

[0082] Optionally, the curvature of the reflective surface 40 is the same as the curvature of the human eye surface to avoid affecting the human eye's view of the real external scene.

[0083] This application also provides an augmented reality device, which includes a housing and an optical engine module as described above, the optical engine module being mounted on the housing.

[0084] Augmented reality devices can be electronic devices such as glasses, helmets, tablets, mobile phones, and projectors. By employing the aforementioned optical engine modules, augmented reality devices can achieve a large field of view with a smaller size, improving the user experience.

[0085] For example, if the augmented reality device is a pair of glasses, by using the aforementioned optical engine module, the lenses of the glasses can be made thinner, thus making the shape of the glasses closer to that of everyday glasses.

[0086] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optomechanical module, characterized in that: include: A laser light source (10) is used to provide laser light; A spatial light modulator (20) is used to modulate the laser beam and form an imaging beam. The laser beam emitted by the laser source (10) is incident on the spatial light modulator at a first incident angle. The total internal reflection prism (30) is used to project imaging light emitted from the spatial light modulator (20) at a second incident angle onto the first reflecting surface of the total internal reflection prism (30) and onto the first mirror surface (50) after at least one total internal reflection. The surface of the first mirror surface (50) has a polarizing beam splitting film. A reflective surface (40) has a semi-transparent and semi-reflective film (41) on its surface, which is used to reflect the imaging light reflected by the first mirror (50) into the human eye.

2. The optomechanical module as described in claim 1, characterized in that: The first incident angle is θ1, θ1=[arctan(1 / F#)]*180 / π, where F# is the F number of the optical system between the laser source (10) and the spatial light modulator (20); The second incident angle is θ2, θ2-θ1≥θc, where θc is the critical angle for total internal reflection of the total internal reflection prism (30).

3. The optomechanical module as described in claim 1, characterized in that: The imaging light emitted from the spatial light modulator (20) undergoes at least two total internal reflections within the total internal reflection prism (30).

4. The optomechanical module as described in claim 1, characterized in that: The optomechanical module also includes a cemented prism (51) and a compensating lens (60). The cemented surface of the cemented prism (51) forms the first mirror surface (50), and the compensating lens (60) is disposed on the curved side of the reflective surface (40).

5. The optomechanical module as described in claim 4, characterized in that: The total internal reflection prism (30) and the cemented prism (51) are an integral structure.

6. The optomechanical module as described in claim 1, characterized in that: The first mirror (50) is a plane mirror (52), and the plane mirror (52) and the reflecting surface (40) form a hollow mirror. The polarizing light-emitting film is disposed on the side of the plane mirror (52) facing the reflecting surface (40).

7. The optomechanical module as described in claim 6, characterized in that: The optomechanical module also includes a first lens (70), which is disposed between the first mirror (50) and the total internal reflection prism (30).

8. The optomechanical module as described in any one of claims 1 to 7, characterized in that: A quarter-wave plate (42) is provided between the first mirror (50) and the reflecting surface (40).

9. The optomechanical module as described in claim 1, characterized in that: The laser source (10) includes a red laser source (13), a green laser source (11), a blue laser source (12), a diffractive optical element (14), and a beam combiner. A diffractive optical element (14) is provided for each of the red laser source (13), the green laser source (11), and the blue laser source (12). The beam combiner is used to combine the three colors of laser light passing through the diffractive optical element (14) into a white laser. A half-wave plate (18) is provided between the red laser source (13) and the corresponding diffractive optical element (14).

10. The optomechanical module as described in claim 1, characterized in that: The optomechanical module further includes a second lens (80), which is located between the laser source (10) and the total internal reflection prism (30), and the spatial light modulator (20) is located at the focal plane of the second lens (80).

11. The optomechanical module as described in claim 1, characterized in that: The spatial light modulator (20) is a DMD chip; And / or, the surface curvature of the reflective surface (40) is the same as the surface curvature of the human eye.

12. An augmented reality device, characterized in that: include: shell; The optical engine module as described in any one of claims 1 to 11, wherein the optical engine module is mounted on the housing.

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