阅读说明：本技术 用于rgb照明器的方法和系统 (Method and system for RGB luminaire ) 是由 K·乌伦多尔夫 于 2019-06-21 设计创作，主要内容包括：一种光学组合器包括被配置为旋转通过角度位移范围的旋转镜。在第一时间段期间,旋转镜被设置在第一角度位移处,并且被配置为接收第一入射光束并沿着输出光轴提供第一输出光束。在第二时间段期间,旋转镜被设置在第二角度位移处,并且被配置为接收第二入射光束并沿着输出光轴提供第二输出光束。光学组合器被配置为沿着输出光轴提供时间序列的准直组合输出光束。在光学组合器中,旋转镜还可以被配置为使组合输出光束抖动。(An optical combiner includes a turning mirror configured to rotate through a range of angular displacements. During a first time period, the rotating mirror is disposed at a first angular displacement and is configured to receive a first incident light beam and provide a first output light beam along an output optical axis. During a second time period, the rotating mirror is disposed at a second angular displacement and is configured to receive a second incident light beam and provide a second output light beam along the output optical axis. The optical combiner is configured to provide a time series of collimated combined output beams along an output optical axis. In the optical combiner, the turning mirror may also be configured to dither the combined output beam.)

1. An optical combiner, comprising:

an input mirror assembly configured to receive the plurality of light beams and provide a first reflected light beam, a second reflected light beam, and a third reflected light beam; and

a rotating mirror configured to rotate through a range of angular displacements, wherein:

during a first time period, the rotating mirror is disposed at a first angular displacement and is configured to receive the first reflected beam from the input mirror assembly and provide a first output beam along an output optical axis; and

during a second time period, the rotating mirror is disposed at a second angular displacement and is configured to receive the second reflected beam from the input mirror assembly and provide a second output beam along the output optical axis; and

during a third time period, the rotating mirror is disposed at a third angular displacement and is configured to receive the third reflected beam from the input mirror assembly and provide a third output beam along the output optical axis;

wherein the optical combiner is configured to provide a time series of collimated combined output beams along the output optical axis and to dither the combined output beams.

2. The optical combiner of claim 1, wherein the input mirror assembly comprises:

a first input mirror disposed in a first optical path between the rotating mirror and a first light source and configured to reflect a first input light beam emitted from the first light source and direct the first reflected light beam to the rotating mirror during the first period of time when the rotating mirror is at the first angular displacement;

a second input mirror disposed in a second optical path between the rotating mirror and a second light source and configured to reflect a second input light beam emitted from the second light source and direct the second reflected light beam to the rotating mirror during the second time period when the rotating mirror is at the second angular displacement; and

a third input mirror disposed in a third optical path between the rotating mirror and a third light source and configured to reflect a third input light beam emitted from the third light source and direct the third reflected light beam to the rotating mirror during the third time period when the rotating mirror is at the third angular displacement.

3. The optical combiner of claim 2, wherein the first light source is a red laser light source, the second light source is a green laser light source, and the third light source is a blue laser light source, wherein each of the first, second, and third input mirrors is a collimating and rounding mirror.

4. The optical combiner of claim 3, wherein the first light source, the second light source, the third light source, and the input mirror assembly are arranged in a two-dimensional planar configuration with the rotating mirror arranged offset in a third dimension to provide a folded optical path to reduce a size of the optical combiner.

5. The optical combiner of claim 1, wherein the input mirror assembly comprises a curved reflective element configured to:

reflecting a first input light beam emitted from a first light source to the rotating mirror during the first period of time in which the rotating mirror is at the first angular displacement; and

reflecting a second input light beam emitted from a second light source to the rotating mirror during the second time period in which the rotating mirror is at the second angular displacement; and

reflecting a third input light beam emitted from a third light source to the rotating mirror during the third time period when the rotating mirror is at the second angular displacement.

6. The optical combiner of claim 5, wherein the curved reflective element comprises a discrete prescription for each individual incident position on the curved reflective element.

7. The optical combiner of claim 5, wherein the curved reflective element comprises a parabolic surface profile.

8. The optical combiner of claim 5, wherein the curved reflective element comprises an elliptical surface profile.

9. The optical combiner of claim 5, wherein the curved reflective elements comprise hyperbolic surface profiles.

10. The optical combiner of claim 5, wherein the rotating mirror is a one-axis MEMS mirror.

11. The optical combiner of claim 5, wherein the rotating mirror is a biaxial MEMS mirror.

12. An RGB (red green blue) illuminator comprising the optical combiner of claim 1, a red laser light source, a green laser light source, and a blue laser light source.

13. An optical combiner comprising a turning mirror configured to rotate through a range of angular displacements, wherein:

during a first time period, the rotating mirror is disposed at a first angular displacement and is configured to receive a first incident light beam and provide a first output light beam along an output optical axis; and

during a second time period, the rotating mirror is disposed at a second angular displacement and is configured to receive a second incident light beam and provide a second output light beam along the output optical axis;

whereby the optical combiner is configured to provide a time series of collimated combined beams.

14. The optical combiner of claim 13, wherein the rotating mirror is configured to dither the first and second output beams.

15. The optical combiner of claim 13, further comprising an input mirror assembly configured to:

receiving a first input light beam and a second input light beam from a first light source and a second light source, respectively;

reflecting the first input light beam to form a first reflected light beam to provide the first incident light beam to the rotating mirror; and

reflecting the second input light beam to form a second reflected light beam to provide the second incident light beam to the rotating mirror.

16. The optical combiner of claim 15, wherein the input mirror assembly comprises:

a first input mirror disposed in a first optical path between the rotating mirror and the first light source and configured to reflect the first input light beam emitted from the first light source and direct the first reflected light beam to the rotating mirror during the first period of time when the rotating mirror is at the first angular displacement, wherein the first reflected light beam forms the first incident light beam to the rotating mirror; and

a second input mirror disposed in a second optical path between the rotating mirror and the second light source and configured to reflect the second input light beam emitted from the second light source and direct the second reflected light beam to the rotating mirror during the second time period when the rotating mirror is at the second angular displacement, wherein the second reflected light beam forms the second incident light beam to the rotating mirror.

17. The optical combiner of claim 16, wherein the first and second input mirrors are collimating and circularizing mirrors.

18. The optical combiner of claim 15, wherein the input mirror assembly comprises a curved reflective element configured to:

reflecting the first input light beam emitted from the first light source to the rotating mirror during the first period of time in which the rotating mirror is at the first angular displacement; and

reflecting the second input light beam emitted from the second light source to the rotating mirror during the second time period in which the rotating mirror is at the second angular displacement.

19. The optical combiner of claim 18, wherein the curved reflective element comprises a discrete prescription for each individual incident position on the curved reflective element.

20. The optical combiner of claim 18, wherein the curved reflective element comprises a parabolic surface profile.

21. The optical combiner of claim 18, wherein the curved reflective element comprises an elliptical surface profile.

22. The optical combiner of claim 18, wherein the curved reflective elements comprise hyperbolic surface profiles.

23. The optical combiner of claim 13, wherein the rotating mirror is a one-axis MEMS mirror.

24. The optical combiner of claim 13, wherein the rotating mirror is a biaxial MEMS mirror.

25. An RGB (red green blue) illuminator comprising the optical combiner of claim 13, a red laser light source, a green laser light source, and a blue laser light source.

26. A method for combining light beams from a plurality of light sources, comprising:

during a first time period, setting a rotating mirror at a first angular displacement and receiving a first incident light beam to provide a first output light beam along an output optical axis; and

during a second time period, setting the rotating mirror at a second angular displacement and receiving a second incident light beam to provide a second output light beam along the output optical axis;

the above process is repeated to provide a time series of collimated combined output beams along the output optical axis.

27. The method of claim 26, further comprising: during a third time period, the rotating mirror is disposed at a third angular displacement and receives a third incident light beam to provide a third output light beam along the output optical axis.

28. The method of claim 26, further comprising: dithering the combined output beam using the turning mirror.

29. The method of claim 26, further comprising:

receiving, using an input mirror assembly, first and second input light beams from first and second light sources, respectively;

reflecting the first input light beam using the input mirror assembly to form a first reflected light beam to provide the first incident light beam to the rotating mirror; and

reflecting the second input light beam using the input mirror assembly to form a second reflected light beam to provide the first incident light beam to the turning mirror.

30. The method of claim 29, further comprising: collimating and rounding the first output beam and the second output beam using the input mirror assembly.

31. The method of claim 29, wherein the input mirror assembly comprises:

a first input mirror disposed in a first optical path between the rotating mirror and the first light source and configured to reflect the first input light beam emitted from the first light source and direct the first reflected light beam to the rotating mirror during the first period of time when the rotating mirror is at the first angular displacement, wherein the first reflected light beam forms the first incident light beam to the rotating mirror; and

a second input mirror disposed in a second optical path between the rotating mirror and the second light source and configured to reflect the second input light beam emitted from the second light source and direct the second reflected light beam to the rotating mirror during the second time period when the rotating mirror is at the second angular displacement, wherein the second reflected light beam forms the second incident light beam to the rotating mirror.

32. The method according to claim 29, wherein the input mirror assembly comprises a curved reflective element configured to:

reflecting the first input light beam emitted from the first light source to the rotating mirror during the first period of time in which the rotating mirror is at the first angular displacement; and

reflecting the second input light beam emitted from the second light source to the rotating mirror during the second time period in which the rotating mirror is at the second angular displacement.

33. The method of claim 32, wherein the curved reflective element comprises a parabolic surface profile.

34. The method of claim 32, wherein the curved reflective element comprises an elliptical surface profile.

35. The method of claim 32, wherein the curved reflective elements comprise hyperbolic surface profiles.

36. The method of claim 32, further comprising: an RGB (red green blue) illuminator formed using the method of claim 26 to combine light beams from a red laser light source, a green laser light source, and a blue laser light source.

37. An optical combiner comprising a dichroic mirror assembly comprising a first dichroic mirror, a second dichroic mirror, and a third dichroic mirror arranged in a stack along an output optical axis, wherein:

the first dichroic mirror is configured to reflect light of a first color;

the second dichroic mirror is configured to reflect light of a second color and transmit light of the first color; and

the third dichroic mirror is configured to reflect light of a third color and transmit light of the first color and light of the second color;

wherein:

the first dichroic mirror is disposed at a first angular displacement and is configured to receive a first incident light beam of the first color and provide a first output light beam along the output optical axis;

the second dichroic mirror is disposed at a second angular displacement and is configured to receive a second incident light beam of the second color and provide a second output light beam along the output optical axis;

the third dichroic mirror is disposed at a third angular displacement and is configured to receive a third incident light beam of the third color and provide a third output light beam along the output optical axis;

whereby the optical combiner is configured to provide a collimated combined output beam along the output optical axis.

38. The optical combiner of claim 37, wherein:

a portion of the first incident light beam passes through the third dichroic mirror and the second dichroic mirror before reaching the first dichroic mirror; and

a portion of the second incident light beam passes through the third dichroic mirror before reaching the second dichroic mirror.

39. The optical combiner of claim 37, wherein:

a portion of the first output light beam passes through the second dichroic mirror and the third dichroic mirror before reaching the first dichroic mirror; and

a portion of the second output light beam passes through the third dichroic mirror before reaching the second dichroic mirror.

40. The optical combiner of claim 37, further comprising an input mirror assembly configured to:

receiving first, second, and third input light beams from first, second, and third light sources, respectively;

reflecting the first input light beam to form a first reflected light beam to provide the first incident light beam to the dichroic mirror assembly;

reflecting the second input light beam to form a second reflected light beam to provide the second incident light beam to the dichroic mirror assembly; and

reflecting the third input light beam to form a third reflected light beam to provide the third incident light beam to the dichroic mirror assembly.

41. The optical combiner of claim 40, wherein the input mirror assembly comprises:

a first input mirror disposed in a first optical path between the dichroic mirror assembly and the first light source and configured to reflect the first input light beam emitted from the first light source and direct the first reflected light beam to the dichroic mirror assembly, wherein the first reflected light beam forms the first incident light beam to the dichroic mirror assembly;

a second input mirror disposed in a second optical path between the dichroic mirror assembly and the second light source and configured to reflect the second input light beam emitted from the second light source and direct the second reflected light beam to the dichroic mirror assembly, wherein the second reflected light beam forms the second incident light beam to the dichroic mirror assembly; and

a third input mirror disposed in a third optical path between the dichroic mirror assembly and the third light source and configured to reflect the second input light beam emitted from the third light source and direct the third reflected light beam to the dichroic mirror assembly, wherein the second reflected light beam forms the second incident light beam to the dichroic mirror assembly.

42. The optical combiner of claim 41, wherein the first, second and third input mirrors in the input mirror assembly are collimating and circularizing mirrors.

43. The optical combiner of claim 40, wherein the input mirror assembly comprises a curved reflective element configured to:

reflecting the first input light beam emitted from the first light source to the dichroic mirror assembly; and

reflecting the second input light beam emitted from the second light source to the dichroic mirror assembly; and

reflecting the third input light beam emitted from the third light source to the dichroic mirror assembly.

44. The optical combiner of claim 43, wherein the curved reflective element comprises a discrete prescription for each individual incident position on the curved reflective element.

45. The optical combiner of claim 43, wherein the curved reflective element comprises a parabolic surface profile.

46. The optical combiner of claim 43, wherein the curved reflective element comprises an elliptical surface profile.

47. The optical combiner of claim 43, wherein the curved reflective elements comprise hyperbolic surface profiles.

48. An RGB (red green blue) illuminator comprising the optical combiner of claim 37, a red laser light source, a green laser light source, and a blue laser light source.

Background

Modern computing and display technology has facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally-generated images are presented to a user in a wearable device in a manner in which they appear to be real or can be perceived as real. Virtual reality or "VR" scenes typically involve the presentation of digital or virtual image information, while being opaque to other actual real-world visual inputs; augmented reality or "AR" scenes typically involve the presentation of digital or virtual image information as an augmentation to the visualization of the real world around the user.

The wearable device may include augmented and/or virtual reality glasses. The image may be displayed using an image frame or a raster scan image. In these display devices, optical combiners are commonly used to combine light beams from different light sources. For example, red, green, and blue beams may be combined to form a collimated combined color beam for displaying an image. Conventional optical combiners made with glass lenses, mirrors, and prisms can be bulky and heavy. They are undesirable for wearable devices in VR or AR applications.

Accordingly, improved structures and methods for optical combiners are highly desirable.

Disclosure of Invention

Embodiments of the present invention provide methods and systems for an RGB (red green blue) illuminator that is compact and lightweight compared to conventional combiners. Some embodiments may also provide speckle reduction. In embodiments of the present invention, the optical combiner may combine light beams from two or more light sources (such as laser diodes). In some embodiments, the mirror assembly reflects the light beams from the light sources toward a combining element that produces a combined output light beam along a common optical axis. Mirrors direct the beams to the combining elements to achieve collinearity. The spatial arrangement of the mirror assembly and the combining elements provides a folded optical path to reduce the size of the optical combiner. The mirror assembly may be a collection of mirrors or a single reflective element. Collimation and circularization can be achieved by a combination of refractive lenses (e.g., annular) and mirrors (rotationally symmetric/off-axis parabolic or free form). These elements may be separate for each source or the same for each source. Thus, it can be a "segmented/discrete" solution or a monolithic solution (monolithic solution) for each element.

The combining element may be a stack of dichroic mirrors, a prism configuration based on the combination of dichroic light beams, a diffractive element or a MEMS (micro-electro-mechanical system) mirror. For example, the combining element may be a rotating MEMS mirror that is tilted at different angular displacements for each light source. For coherent sources, an Etendue (Etendue) element (e.g., a holographic diffuser) may be combined to achieve speckle reduction by wobbling the combining element to slightly shift the beam. Embodiments based on rotating MEMS mirrors can provide dithering of the optical beam without the need for additional components. In other embodiments, providing beam dithering would require additional actuators.

According to some embodiments of the invention, the optical combiner includes an input mirror assembly configured to receive the plurality of light beams and provide a first reflected light beam, a second reflected light beam, and a third reflected light beam. The optical combiner also includes a turning mirror configured to turn through a range of angular displacements. During a first time period, the rotating mirror is disposed at a first angular displacement and is configured to receive a first reflected light beam from the input mirror assembly and provide a first output light beam along an output optical axis. During a second time period, the rotating mirror is disposed at a second angular displacement and is configured to receive a second reflected light beam from the input mirror assembly and provide a second output light beam along the output optical axis. During a third time period, the rotating mirror is disposed at a third angular displacement and is configured to receive a third reflected light beam from the input mirror assembly and provide a third output light beam along the output optical axis. The optical combiner is configured to provide a time series of collimated combined output beams along an output optical axis and to dither the combined output beams.

In some embodiments of the above optical combiner, the input mirror assembly includes a first input mirror disposed in a first optical path between the rotating mirror and the first light source and configured to reflect a first input light beam emitted from the first light source and direct a first reflected light beam to the rotating mirror during a first time period when the rotating mirror is at the first angular displacement. The input mirror assembly further includes a second input mirror disposed in a second optical path between the rotating mirror and the second light source and configured to reflect a second input light beam emitted from the second light source and direct a second reflected light beam to the rotating mirror during a second time period when the rotating mirror is at a second angular displacement. The input mirror assembly further includes a third input mirror disposed in a third optical path between the rotating mirror and the third light source and configured to reflect a third input light beam emitted from the third light source and direct a third reflected light beam to the rotating mirror during a third time period when the rotating mirror is at a third angular displacement.

In some embodiments of the above optical combiner, the first light source is a red laser light source, the second light source is a green laser light source, and the third light source is a blue laser light source. Each of the first input mirror, the second input mirror, and the third input mirror is a collimating and circularizing mirror.

In some embodiments, the first light source, the second light source, the third light source, and the input mirror assembly are arranged in a two-dimensional planar configuration, and the turning mirror is offset in a third dimension to provide a folded optical path, thereby reducing the size of the optical combiner.

In an alternative embodiment, the input mirror assembly may include a curved reflective element configured to reflect a first input light beam emitted from the first light source to the rotating mirror during a first time period when the rotating mirror is at the first angular displacement, to reflect a second input light beam emitted from the second light source to the rotating mirror during a second time period when the rotating mirror is at the second angular displacement, and to reflect a third input light beam emitted from the third light source to the rotating mirror during a third time period when the rotating mirror is at the second angular displacement.

In some embodiments, the curved reflective element may have a discrete prescription for each individual incident location on the curved reflective element. In some embodiments, the curved reflective element may have a parabolic surface profile. In some embodiments, the curved reflective element may have an elliptical surface profile. In some embodiments, the curved reflective elements may have hyperbolic surface profiles.

According to an embodiment, the rotating mirror may be a one-axis MEMS mirror or a two-axis MEMS mirror.

In some embodiments, the RGB illuminator includes red, green, and blue laser light sources and an optical combiner as above.

According to some embodiments, the optical combiner may include a turning mirror configured to rotate through a range of angular displacements. During a first time period, the rotating mirror is disposed at a first angular displacement and is configured to receive a first incident light beam and provide a first output light beam along an output optical axis. During a second time period, the rotating mirror is disposed at a second angular displacement and is configured to receive a second incident light beam and provide a second output light beam along the output optical axis. The optical combiner is configured to provide a time series of collimated combined beams.

In some embodiments of the above optical combiner, the turning mirror is configured to dither the first output beam and the second output beam.

In some embodiments, the optical combiner further comprises an input mirror assembly configured to receive the first and second input beams from the first and second light sources, respectively; reflecting the first input light beam to form a first reflected light beam to provide the first incident light beam to the rotating mirror; and reflecting the second input light beam to form a second reflected light beam to provide the second incident light beam to the rotating mirror.

In some embodiments, the input mirror assembly includes a first input mirror disposed in a first optical path between the rotating mirror and the first light source and configured to reflect a first input light beam emitted from the first light source and direct the first reflected light beam to the rotating mirror during a first time period when the rotating mirror is at the first angular displacement. The first reflected beam forms a first incident beam to the rotating mirror. The input mirror assembly further includes a second input mirror disposed in a second optical path between the rotating mirror and the second light source and configured to reflect a second input light beam emitted from the second light source and direct a second reflected light beam to the rotating mirror during a second time period when the rotating mirror is at a second angular displacement. The second reflected beam forms a second incident beam to the turning mirror.

In some embodiments, the first input mirror and the second input mirror are collimating and circularizing mirrors.

In some embodiments, the input mirror assembly may include a curved reflective element configured to reflect a first input light beam emitted from the first light source to the rotating mirror during a first time period in which the rotating mirror is at the first angular displacement; and reflecting a second input light beam emitted from a second light source to the rotating mirror during a second time period in which the rotating mirror is at a second angular displacement.

According to some embodiments, a method for combining light beams from a plurality of light sources comprises: during a first time period, the rotating mirror is disposed at a first angular displacement and receives a first incident light beam to provide a first output light beam along an output optical axis. The method includes, during a second time period, setting the rotating mirror at a second angular displacement and receiving a second incident light beam to provide a second output light beam along the output optical axis. The method further includes repeating the above operations to provide a time series of collimated combined output beams along an output optical axis.

In some embodiments, the method may further include: during a third time period, the rotating mirror is disposed at a third angular displacement and receives a third incident light beam to provide a third output light beam along the output optical axis.

In some embodiments, the method may further comprise dithering the combined output beam using a rotating mirror.

In some embodiments, the method may further include receiving, using an input mirror assembly, first and second input light beams from the first and second light sources, respectively. The method may also include reflecting the first input light beam using an input mirror assembly to form a first reflected light beam to provide the first incident light beam to a rotating mirror; and reflecting the second input light beam using an input mirror assembly to form a second reflected light beam to provide the first incident light beam to the turning mirror.

In some embodiments, the method further comprises collimating and rounding the first output beam and the second output beam using the input mirror assembly.

According to some embodiments, an optical combiner has a dichroic mirror assembly including a first dichroic mirror, a second dichroic mirror, and a third dichroic mirror arranged in a stack along an output optical axis. The first dichroic mirror is configured to reflect the light beam of the first color. The second dichroic mirror is configured to reflect the light beam of the second color and transmit the light beam of the first color. The third dichroic mirror is configured to reflect the light beam of the third color and transmit the light beam of the first color and the light beam of the second color. The first dichroic mirror is disposed at a first angular displacement and is configured to receive a first incident light beam of a first color and provide a first output light beam along an output optical axis. The second dichroic mirror is disposed at a second angular displacement and is configured to receive a second incident light beam of a second color and provide a second output light beam along the output optical axis. The third dichroic mirror is disposed at a third angular displacement and is configured to receive a third incident light beam of a third color and provide a third output light beam along the output optical axis. The optical combiner is configured to provide a collimated combined output beam along an output optical axis. In an alternative embodiment, the first dichroic mirror may be replaced with a mirror.

In some embodiments, a portion of the first incident light beam passes through the third dichroic mirror and the second dichroic mirror before reaching the first dichroic mirror, and a portion of the second incident light beam passes through the third dichroic mirror before reaching the second dichroic mirror.

According to some embodiments, a method for combining light beams from a plurality of light sources includes providing a dichroic mirror assembly comprising a first dichroic mirror, a second dichroic mirror, and a third dichroic mirror arranged in a stack along an output optical axis. The first dichroic mirror is configured to reflect the light beam of the first color. The second dichroic mirror is configured to reflect the light beam of the second color and transmit the light beam of the first color. The third dichroic mirror is configured to reflect the light beam of the third color and transmit the light beam of the first color and the light beam of the second color. The method includes disposing a first dichroic mirror at a first angular displacement to receive a first incident light beam of a first color and provide a first output light beam along an output optical axis. The method also includes disposing a second dichroic mirror at a second angular displacement to receive a second incident light beam of a second color and provide a second output light beam along the output optical axis. The method also includes disposing a third dichroic mirror at a third angular displacement to receive a third incident light beam of a third color and provide a third output light beam along the output optical axis. The method configures an optical combiner to provide a collimated combined output beam along an output optical axis. In an alternative embodiment, the first dichroic mirror may be replaced with a mirror.

In some embodiments, the method may further include dithering the combined output beam using a rotating mirror.

Additional features, benefits and embodiments are described in the detailed description, figures and claims below.

Drawings

Fig. 1 is a perspective view of exemplary augmented reality glasses, according to some embodiments;

fig. 2 is a top view of example augmented reality glasses, according to some embodiments;

FIG. 3 is a perspective view showing an optical illuminator according to some embodiments of the present invention;

4A, 4B, and 4C are simplified schematic diagrams illustrating the operation of optical combiners according to some embodiments of the present invention;

FIG. 5 is a timing diagram illustrating the operation of an optical illuminator according to some embodiments of the invention;

FIG. 6 is a perspective view showing another optical illuminator in accordance with some embodiments of the invention;

FIGS. 7A and 7B are perspective views of a 1-axis turning mirror and a 2-axis turning mirror that may be used in an optical illuminator;

FIG. 8 is a flow chart illustrating a method for an optical combiner according to some embodiments of the present invention; and

FIG. 9 is a perspective view illustrating yet another optical illuminator in accordance with some embodiments of the invention.

Detailed Description

Embodiments of the present invention relate to optical combiner systems and methods to provide an optical illuminator for a wearable device for projecting light beams from multiple light sources.

Fig. 1 is a perspective view of example augmented reality glasses 100, according to some embodiments. Augmented reality glasses 100 are examples of wearable devices for virtual reality or augmented reality applications. As shown in fig. 1, wearable display device 100 may include a frame 110 supporting a left waveguide eyepiece 120L and a right waveguide eyepiece 120R. Each of the waveguide eyepieces 120L and 120R may include an in-coupling grating (ICG)121, an Orthogonal Pupil Expander (OPE)122, and an Exit Pupil Expander (EPE) 123. The in-coupling grating is also referred to as an in-coupling port. The in-coupling grating (ICG)121, the Orthogonal Pupil Expander (OPE)122 and the Exit Pupil Expander (EPE)123 may be suitable Diffractive Optical Elements (DOEs). For example, they may take the form of gratings formed on optical waveguides. According to some embodiments, instead of providing a single waveguide for each eyepiece, each eyepiece may have a stack of multiple optical waveguides for different colors and with different optical powers EPE. The EPE is configured to project an image viewable from the user eye position 130.

In fig. 1, incident light (which may be image light or a scanning beam) may be incident on the ICG (121) of each eyepiece 120L, 120R. Each ICG 121 couples incident light to a guided mode that propagates in a direction toward OPE region 122. The eyepiece propagates the image light by Total Internal Reflection (TIR). The OPE region 122 of each eyepiece 120L, 120R may also include a diffractive element that couples and redirects a portion of the image light propagating in the eyepiece 120L, 120R toward the EPE region 123. EPE region 123 includes diffractive elements that couple and direct a portion of the light propagating in each eyepiece 120L, 120R in a direction out of the plane of eyepiece layer 120 and toward eye position 130 of the viewer. In this way, the image can be viewed by the viewer.

The incident light may include light of three primary colors, i.e., blue (B), green (G), and red (R).

In some applications, the eyepiece may accept collimated light that is scanned in two degrees of freedom. Each instantaneous angle of incidence (or small range of angles of incidence) corresponds to a pixel defined in angle. In some embodiments, the light may be configured to simulate a virtual object that may appear to be some distance away from the viewer, e.g., half a meter to one meter.

Fig. 2 is a top view of example augmented reality glasses 200, according to some embodiments. Augmented reality glasses 200 are an example of a wearable device for virtual reality or augmented reality applications. As shown in fig. 2, wearable display device 200 may include a frame 210 and an eyepiece 220. Each eyepiece may be similar to eyepieces 120L, 120R in fig. 1 and may include ICG, OPE, and EPE, which are not visible in top view. The wearable display device 200 can also include a scanner housing 230, which scanner housing 230 can include a scanning mirror for forming a virtual image (e.g., at infinity) from an incident light source. In some embodiments, an ICG is used as an input port to receive light. The image formed by the eyepiece may be viewed from the user eye position 240. The augmented reality glasses may also have a left speaker 250 and a camera 260.

As above, the incident light may include light in three primary colors, i.e., blue (B), green (G), and red (R). In some embodiments, the beams of incident light are combined in an optical combiner. For wearable devices for VR and AR applications, it is desirable that the optical combiner in the system be compact and lightweight.

FIG. 3 is a perspective view illustrating an optical illuminator according to some embodiments of the present invention. As shown in fig. 3, optical illuminator 300 includes an optical combiner (also referred to as a combining element) and three light sources. The optical combiner 390 may include an input mirror assembly 310, the input mirror assembly 310 configured to receive light beams from two or more light sources and provide two or more reflected light beams. Optical combiner 390 also has a turning mirror 320, with turning mirror 320 configured to rotate through a range of angular displacements. The turning mirror 320 is also configured to receive two or more reflected beams to provide a time series of collimated combined output beams along an output optical axis. Turning mirror 320 is an example of a combination element.

In fig. 3, the light source includes three laser light sources, including a first light source 301, a second light source 302 (hidden in fig. 3), and a third light source 303. In this example, the first light source emits a red light beam 331, the second light source 302 emits a green light beam 332, and the third light source 303 emits a blue light beam 333. Input mirror assembly 310 may include two or more input mirrors. In the embodiment of fig. 3, the input mirror assembly 310 comprises a first input mirror 311, a second input mirror 312 and a third input mirror 313. The three input mirrors in input mirror assembly 310 are configured to receive a light beam from a light source and provide a reflected light beam to turning mirror 320. For example, the first input mirror 311 receives the red light beam 331 from the red laser light source 301 and reflects the red reflected light beam 341 toward the rotating mirror 320. The second mirror 312 receives the green input light beam 332 from the green laser light source 302 and reflects the green reflected light beam 342 towards the turning mirror 320. The third input mirror 313 receives the blue light beam 333 from the blue laser light source 303 and reflects the blue reflected light beam 343 toward the rotating mirror 320.

The beam output by an edge-emitting laser diode may have different parallel and perpendicular divergence angles, resulting in an elliptical beam spot, rather than a circularly symmetric spot. In some embodiments, first input mirror 311, second input mirror 312, and third input mirror 313 can provide collimation and circularization of the light beam. Collimation and circularization can be achieved by a combination of refractive lenses (e.g., annular) and mirrors (rotationally symmetric/off-axis parabolic or free form).

In some embodiments of the present invention, turning mirror 320 is configured to rotate through a range of angular displacements. In FIG. 3, rotating mirror 320 is shown at three different angular displacements: position 321, which indicates that the rotating mirror is at a first angular displacement; position 322, which indicates that the turning mirror is at a second angular displacement; and position 323 indicating that the rotating mirror is at the third angular displacement.

Optical combiner 390 is configured to provide a time series of collimated combined output beams 350 along output optical axis 360. During the first time period, the turning mirror 320 is disposed at the first angular displacement 321 and is configured to receive the first reflected light beam 341 from the input mirror assembly and provide a first output light beam 351 along the output optical axis 360. During the second time period, the turning mirror 320 is disposed at the second angular displacement 322 and is configured to receive the second reflected light beam 342 from the input mirror assembly and provide a second output light beam 352 along the output optical axis 360. In the example of fig. 3, three light sources are provided and during a third time period, the rotating mirror 320 is disposed at a third angular displacement 323 and is configured to receive a third reflected light beam 343 from the input mirror assembly 310 and provide a third output light beam 353 along the output optical axis 360. Optical combiner 390 is configured to provide a time series of collimated combined output beams 350 along an output optical axis. The time series of collimated combined output beams 350 includes output beams 351, 352 and 353 originating from three different light sources.

Optical combiner 390 is configured to receive light beams from the red, green, and blue light sources to provide a time series of collimated combined red, green, and blue (RGB) output light beams. In fig. 3, a controller 380 is shown coupled to light sources 301, 302, and 303 and rotating mirror 320 for controlling the timing of the rotation of rotating mirror 320 and the emission of the light beam. As shown in fig. 3, the light sources 301, 302, and 303 and the input mirrors 311, 312, and 313 may be arranged in a two-dimensional planar configuration. The turning mirror may be offset in a third dimension. The spatial arrangement of the input mirror assembly and the combining element (in this case, the turning mirror) provides a folded optical path to reduce the size of the optical combiner. In some embodiments, optical illuminator 300 may be formed in a 2mm by 2mm or 3mm by 3mm package (package). Further, the turning mirror 320 may be a MEMS mirror, which may be lighter than conventional glass combiners.

In some embodiments, rotating mirror 320 may be configured to provide dithering of output beam 350 to reduce speckle. Speckle patterns can occur when monochromatic light, such as laser light, reflects off an imperfect reflective surface. The speckle effect is the result of interference of many waves of the same frequency, with different phases and amplitudes, which add up to give a composite wave whose amplitude and hence intensity vary randomly. Providing dithering of the mirror can reduce speckle. In some embodiments, dithering vibrations of the reflective surface in combination with the scattering element may be utilized to reduce speckle.

Fig. 4A-4C are simplified schematic diagrams illustrating the operation of an optical combiner according to some embodiments of the present invention. Fig. 4A-4C show top views of optical combiner 390 of fig. 3 during each of three time periods of operation to provide a time series of collimated combined output beams. Fig. 4A shows that during a first time period, rotating mirror 320 is placed at a first angular displacement 321. The first light source 301 emits a first light beam 331 to a first input mirror 311 of an input mirror assembly, which first input mirror 311 directs a reflected light beam 341 towards a turning mirror 320. The turning mirror 320 is configured to receive a first reflected light beam 341 from a first input mirror 311 of the input mirror assembly and to provide a first output light beam 351 along an output optical axis 360. In fig. 4B, rotating mirror 320 is disposed at a second angular displacement 322 during a second time period. The second light source 302 emits a second light beam 332 to a second mirror 312 of the mirror assembly, which second mirror 312 directs a reflected light beam 342 towards the turning mirror 320. Turning mirror 320 is configured to receive second reflected light beam 342 from second mirror 312 of the input mirror assembly and provide a second output light beam 352 along an output optical axis 360. In fig. 4B, elements 302, 312, 332, and 342 are hidden from top view. Thus, for purposes of illustration, these elements are reproduced below the main figure. In fig. 4C, rotating mirror 320 is disposed at a third angular displacement 323 during a third time period. The third light source 303 emits the third light beam 333 to a third mirror 313 of the mirror assembly, which third mirror 313 directs the reflected light beam 343 towards the turning mirror 320. The turning mirror 320 is configured to receive the third reflected light beam 343 from the third mirror 313 of the input mirror assembly and to provide a third output light beam 353 along the output optical axis 360. Optical combiner 390 is configured to provide a time series of collimated combined output beams 350 along output optical axis 360. The time-series of collimated combined output beams 350 includes output beams 351, 352 and 353 originating from three different light sources in a time-series manner.

FIG. 5 is a timing diagram illustrating the operation of an optical combiner according to some embodiments of the present invention. The horizontal axis represents time. The frame duration is shown as having three fields (field) duration, also referred to as three time periods: t1, T2 and T3. Each of the three time periods may be a field duration for a color. For example, the frame duration may have a period length of 1 millisecond to 1000 milliseconds depending on the total integration time, and the field duration may have a period length of 0.25 milliseconds to 500 milliseconds. The first vertical axis 510 shows the illuminator output of the optical illuminator. The second vertical axis 520 shows the angular displacement of a rotating mirror (e.g., a MEMS mirror). The third vertical axis 530 shows the angular displacement of the rotating mirror including the dither component.

During the first period of time, the rotating mirror is at a first angular displacement and the illuminator output is a first output light beam L1 originating from the first light source. Similarly, during a second time period, the rotating mirror is at a second angular displacement and the illuminator output is a second output light beam L2 originating from a second light source. Further, during a third time period or field duration, the rotating mirror is at a third angular displacement and the illuminator output is a third output light beam L3 originating from a third light source. In this example, the first light source is a red laser light source, the second light source is a green laser light source, and the third light source is a blue laser light source. The optical illuminator is configured to provide a time-series of collimated combined output beams including a red beam, a green beam, and a blue beam along an output optical axis.

In fig. 5, a second vertical axis 520 shows the angular displacement of the turning mirror. During a first time period, the rotating mirror is at a first angular displacementSimilarly, during a second time period, the rotating mirror is at a second angular displacementFurther, during a third time period, the rotating mirror is at a third angular displacement

In fig. 5, a third vertical axis 530 shows the angular displacement of the rotating mirror including the dither component. In each time period, the rotating mirror is configured to make a small dithering movement to reduce the speckle effect. For example, the dithering motion may involve the rotating mirror moving an angular displacement of 0.1 to 20 degrees. The dithering motion may have a period length of less than 1 mus (e.g., 0.2 mus) to 100 milliseconds.

FIG. 6 is a perspective view illustrating another optical illuminator in accordance with some embodiments of the invention. As shown in fig. 6, optical illuminator 600 includes an optical combiner 690 and two or more light sources. Optical combiner 690 includes an input mirror assembly 610 configured to receive light beams from two or more light sources and provide two or more reflected light beams. Optical combiner 690 also has a turning mirror 620 configured to receive two or more reflected beams to provide a time series of collimated combined output beams along a common output optical axis.

The optical illuminator 600 in fig. 6 is similar to the optical illuminator 300 in fig. 3. One difference is that input mirror assembly 610 includes a curved reflective element instead of three input mirrors as in input mirror assembly 310 in fig. 3, parabolic mirror 610 is used in the following description as an example of curved reflective element 610. In fig. 6, the light source includes three laser light sources including a first light source 601, a second light source 602, and a third light source 603. In this example, the first light source emits a red light beam 631, the second light source 602 emits a green light beam 632, and the third light source 603 emits a blue light beam 633. In the embodiment of fig. 6, input mirror assembly 610 includes a parabolic mirror configured to receive a light beam from a light source and provide a reflected light beam to turning mirror 620. For example, the first region 611 of the parabolic mirror 610 receives the red light beam 631 from the red laser light source 601 and reflects the red reflected light beam 641 toward the rotating mirror 620. A second region 612 of parabolic mirror 610 receives green light beam 632 from green laser light source 602 and reflects green reflected light beam 642 toward turning mirror 620. The third region 613 of the parabolic mirror 610 receives the blue light beam 633 from the blue laser light source 603 and reflects the blue reflected light beam 643 toward the turning mirror 620.

Similar to turning mirror 320 in fig. 3, turning mirror 620 in fig. 6 is configured to rotate through a range of angular displacements. In fig. 6, rotating mirror 620 is shown at three different angular displacements: position 621, which indicates that the rotating mirror is at a first angular displacement; position 622, which indicates that the rotating mirror is at a second angular displacement; and position 623, which indicates that the turning mirror is at a third angular displacement.

Optical combiner 690 is configured to provide a time series of collimated combined output beams 650 along output optical axis 660. During a first time period, the turning mirror 620 is disposed at a first angular displacement 621 and is configured to receive a first reflected light beam 641 from the input mirror assembly and provide a first output light beam 651 along an output optical axis 660. During a second time period, the turning mirror 620 is disposed at a second angular displacement 622 and is configured to receive a second reflected light beam 642 from the input mirror assembly and provide a second output light beam 652 along the output optical axis 660. In the example of fig. 6, three light sources are provided, and during a third time period, the turning mirror 620 is disposed at a third angular displacement 623 and is configured to receive a third reflected light beam 643 from the input mirror assembly 610 and provide a third output light beam 653 along the output optical axis 660. Optical combiner 690 is configured to provide a time series of collimated combined output beams 650 along an output optical axis. Time series of collimated combined output beams 650 includes output beams 651, 652, and 653 originating from three different light sources.

In some embodiments, input mirror assembly 610 may include a curved reflective element configured to reflect a first light beam emitted from a first light source to the rotating mirror during a first time period when the rotating mirror is at a first angular displacement and to reflect a second input light beam emitted from a second light source to the rotating mirror during a second time period when the rotating mirror is at a second angular displacement. Further, the curved reflective element may be further configured to reflect a third input light beam emitted from a third light source to the rotating mirror during a third time period when the rotating mirror is at the second angular displacement. In some embodiments, the curved reflective element may include a discrete prescription for each individual incident location on the curved reflective element. In some embodiments, the curved reflective elements may comprise elliptical or hyperbolic surface profiles.

Fig. 6 shows an embodiment in which input mirror assembly 610 is a single curved reflective element. The curved reflective element 610 not only has a single reflective surface for the light beams from all the light source channels, but also has a curved surface opposite a linear surface or a surface for reflecting each channel at a substantially common angle. Such a configuration enables a smaller beam diameter per channel than a linear reflector, further enabling a single cylindrical lens to pass light, as opposed to alternative optical lenses required to support a wider beam diameter, which in turn may create aberrations requiring additional optical components.

In some embodiments, the light beams may be incident on the curved reflective element at different locations. In some embodiments, the curved reflective element may have a single prescription for all channels. In some embodiments, the curved reflective element may have a discrete prescription for each individual channel incident position on the curved reflective element. In some embodiments, the curved reflective element may have an elliptical surface profile, such as an elliptical mirror. In some embodiments, the curved reflective element may have a parabolic surface profile, such as a parabolic mirror. In some embodiments, the curved reflective elements may have hyperbolic surface profiles, such as hyperbolic mirrors.

In some embodiments, the curved reflective element may follow a prescription corresponding to the following equation:

where c is the curvature of the base circle radius, k is the conic constant (for a parabola-1), and the coefficient α is a polynomial aspheric coefficient. The output facet of the laser can be offset in z and y to position the laser at the best focus. The curve is defined in the z-y plane and is generally constant in the x-dimension. The x-dimension spans (span) the output from one or more lasers. In some embodiments, x may be swept through an arc. Many embodiments have an aspheric coefficient value a of zero, although in some embodiments at least one aspheric coefficient is non-zero.

In some embodiments, a uniform surface finish (finish) may be applied to the curved reflective element. In some embodiments, a discrete surface finish (refining) per channel incident on the curved reflective element is applied. Although the present invention has been described with reference to some preferred embodiments, various changes and modifications may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In fig. 6, similar to control 380 in fig. 3, controller 680 is coupled to light sources 601, 602, and 603 and rotating mirror 620 for timing control. The control mechanism described above in connection with fig. 5 is also applicable to the optical illuminator 600 of fig. 6. Further, in some embodiments, rotating mirror 620 may be configured to dither combined output beam 350 to reduce speckle. In some embodiments, the curved reflective element 610 may also provide collimation and rounding. For example, a curved reflective element may be provided, wherein two directions/or one direction of the light beam will be collimated, and the light beam may be made circular.

Fig. 7A is a perspective view of a 1-axis turning mirror 710, and fig. 7B is a perspective view of a 2-axis turning mirror 720 that may be used as the turning mirror 320 in the optical illuminator 300 shown in fig. 3 or the turning mirror 620 in the optical illuminator 600 shown in fig. 6. In some embodiments, the 1-axis scanning mirror 710 can be a MEMS one-dimensional rotating mirror configured to rotate in one dimension with a roll axis. The 2-axis scanning mirror 720 can be a MEMS two-dimensional scanning mirror configured to rotate in two dimensions having a pitch axis and a roll axis. In fig. 3 and 6, the rotating mirror is rotated to receive incident beams originating from different light sources to provide a combined collimated time series output beam. The rotating mirror also serves to provide dithering vibration for speckle reduction. According to embodiments, the rotating mirror may be actuated using electrostatic, magnetic, or piezoelectric devices.

FIG. 8 is a flow chart illustrating a method for combining light beams from multiple light sources according to some embodiments of the invention. In some embodiments, a method for combining light beams from a plurality of light sources comprises: during a first time period, the rotating mirror is disposed at a first angular displacement and receives a first incident light beam to provide a first output light beam along an output optical axis. During a second time period, the method includes disposing the rotating mirror at a second angular displacement and receiving a second incident light beam to provide a second output light beam along the output optical axis. The method further includes repeating the above operations to provide a time series of collimated combined output beams along an output optical axis. The method 800 of FIG. 8 may be summarized as follows.

At 810, the method provides a rotating mirror configured to rotate through a range of angular displacements. Examples of turning mirrors are described above in connection with fig. 3-9. The rotating mirror may be a one-axis MEMS (micro-electro-mechanical system) mirror or a two-axis MEMS mirror with a reflective surface. According to an embodiment, the mirror may also provide collimation.

At 820, the method provides an input mirror assembly configured to receive the light beams from the two or more light sources and provide two or more reflected light beams that form an incident light beam to the rotating mirror. Examples of rotating mirrors are described above in connection with fig. 3 and 6. In some embodiments, the input mirror assembly may include two or more separate input mirrors. The first input mirror may be disposed in a first optical path between the rotating mirror and the first light source and configured to reflect a first light beam emitted from the first light source and direct the first reflected light beam to the rotating mirror during a first time period when the rotating mirror is at the first angular displacement. The second input mirror may be disposed in a second optical path between the rotating mirror and the first light source and configured to reflect a second light beam emitted from the second light source and direct the second reflected light beam to the rotating mirror during a second time period in which the rotating mirror is at a second angular displacement. According to embodiments, the mirror assembly may have three or more input mirrors. The mirror may also provide a collimated, rounded output beam.

In an alternative embodiment, the mirror assembly may comprise a curved reflective element configured to reflect a first input light beam emitted from the first light source to the rotating mirror during a first time period when the rotating mirror is at the first angular displacement, and to reflect a second input light beam emitted from the second light source to the rotating mirror during a second time period when the rotating mirror is at the second angular displacement. An example of a curved reflective element is described above in connection with fig. 6.

Steps 830 and 840 summarize the operation of the optical combiner. At 830, during a first time period, the method includes setting the rotating mirror at a first angular displacement and receiving a first incident light beam to provide a first output light beam along an output optical axis. At 840, during a second time period, the method includes setting the rotating mirror at a second angular displacement and receiving a second incident light beam to provide a second output light beam along the output optical axis. The method may further include dithering the output beam using a rotating mirror. Further details regarding operation are described above in connection with fig. 3-8.

At 850, optionally, during a third time period, the method includes setting the rotating mirror at a third angular displacement and receiving a third incident light beam to provide a third output light beam along the output optical axis. According to embodiments, additional incident beams may be used with the rotating mirror at different angular displacements.

At 860, the above process may be repeated to provide a time series of collimated combined output beams along the output optical axis. More details are described above in connection with fig. 3-8.

FIG. 9 is a perspective view illustrating another optical illuminator in accordance with some embodiments of the invention. As shown in fig. 9, optical illuminator 900 includes an optical combiner 990 and two or more light sources, e.g., 901, 902, and 903. Optical combiner 990 includes an input mirror assembly 910 configured to receive light beams from two or more light sources and provide two or more reflected light beams. Optical combiner 990 also has a dichroic mirror assembly 920 configured to receive two or more reflected beams to provide a time series of collimated combined output beams along an output optical axis. Dichroic mirror assembly 920 is another example of a combining element.

Optical illuminator 990 of fig. 9 is similar to optical illuminator 300 of fig. 3. One difference is that turning mirror 320 in fig. 3 is now replaced by dichroic mirror assembly 9202. As shown in fig. 9, the dichroic mirror assembly 920 includes three dichroic mirrors 921, 922 and 923 disposed at three different angular displacements to receive the reflected beams to provide a collimated combined output beam 950 along an output optical axis.

In fig. 9, the light source includes three laser light sources, for example, a first light source 901, a second light source 902 (hidden in fig. 9), and a third light source 903. In this example, the first light source emits a red light beam 931, the second light source 902 emits a green light beam 932, and the third light source 903 emits a blue light beam 933. Input mirror assembly 910 may include two or more input mirrors. In the embodiment of fig. 9, input mirror assembly 910 includes a first input mirror 911, a second input mirror 912, and a third input mirror 913. Each of the three input mirrors in input mirror assembly 910 is configured to receive a light beam from a light source and provide a reflected light beam to turning mirror 920. For example, the first input mirror 911 receives a red light beam 931 from the red laser light source 901 and reflects a red reflected light beam 941 toward the dichroic mirror assembly 920. Second input mirror 912 receives green light beam 932 from green laser light source 902 and reflects green reflected light beam 942 towards dichroic mirror assembly 920. The third input mirror 913 receives the blue light beam 933 from the blue laser light source 903 and reflects the blue reflected light beam 943 toward the dichroic mirror assembly 920.

In the example of fig. 9, dichroic mirror assembly 920 is shown to include three dichroic mirrors. Dichroic mirrors are mirrors that have significantly different reflection or transmission characteristics at two different wavelengths. In this example, the first dichroic mirror 921 in the dichroic mirror assembly 920 is configured to reflect the light beam from the first input mirror 911 in the mirror assembly 920. In the example of fig. 9, the first dichroic mirror 921 is configured to reflect the red light beam. The first dichroic mirror 921 is also configured to transmit green and blue light beams. Second dichroic mirror 922 in dichroic mirror assembly 920 is configured to reflect the light beam from second input mirror 912 in input mirror assembly 910 and transmit the light beam from first input mirror 911. In the example of fig. 9, the second dichroic mirror 922 is configured to reflect the green light beam and transmit the red and blue light beams. Third dichroic mirror 923 in dichroic mirror assembly 920 is configured to reflect the light beam from third input mirror 913 in input mirror assembly 910 and to transmit the light beam from first input mirror 911 and second input mirror 912 in input mirror assembly 910. In the example of fig. 9, the third dichroic mirror 923 is configured to reflect the blue light beam and transmit the red light beam and the green light beam.

Further, the mirrors in the dichroic mirror assembly 920 are oriented such that they reflect light beams from different light sources to produce output light beams along a common optical axis 960, such that the optical combiner 990 is capable of providing a collimated combined output light beam 950 along the common output optical axis 960. The first dichroic mirror 921 in the dichroic mirror assembly 920 is configured to receive the first reflected light beam 941 from the input mirror assembly and provide a first output light beam 951 along the output optical axis 960. A second dichroic mirror 922 in dichroic mirror assembly 920 is configured to receive a second reflected light beam 942 from the input mirror assembly and provide a second output light beam 952 along an output optical axis 960. Third dichroic mirror 923 in dichroic mirror assembly 920 is configured to receive third reflected light beam 943 from input mirror assembly 910 and provide a third output light beam 953 along output optical axis 960. Optical combiner 990 is configured to provide a collimated combined output beam 950 along an output optical axis 960. Further, a portion of the first output light beam passes through the second and third dichroic mirrors before reaching the first dichroic mirror, and a portion of the second output light beam passes through the third dichroic mirror before reaching the second dichroic mirror. As shown in fig. 9, collimated combined output beam 950 includes output beams 951, 952, and 953 from three different light sources 901, 902, and 903.

In some embodiments of optical combiner 990, a portion of the first reflected light beam passes through a third dichroic mirror and a portion of the second dichroic mirror in dichroic mirror assembly 920 before reaching the first dichroic mirror in dichroic mirror assembly 920. Further, a portion of the second reflected beam passes through a third dichroic mirror in dichroic mirror assembly 920 before reaching the second dichroic mirror in dichroic mirror assembly 920. The optical illuminator 900 may also include a controller 980 coupled to the light sources 901, 902, and 903 for timing control.

In a wearable device, the control mechanisms described above may be operatively coupled, e.g., by a wired lead or wireless connection, to a data processing module that may be mounted in various configurations, e.g., fixedly attached to a frame, fixedly attached to a helmet or hat worn by the user, embedded in a headset, or otherwise attached to the user. The data processing module may include one or more processors configured to analyze and process data and/or image information.

While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous variations, modifications, changes, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims.