Beam splitter and coupling prism device

Abstract

The optical system may include: a light guide having a light input end and first and second main outer surfaces parallel to each other for guiding light by internal reflection; a projector configured to project light corresponding to the image from the aperture, the light exiting the aperture with a chief ray defining an optical axis of the projector and with an angular field surrounding the chief ray; and a prism disposed adjacent to the light input and having a partially reflective surface parallel to the first and second major outer surfaces and an image injection surface, the projector associated with the image injection surface and oriented such that at least some of a chief ray and an angular field surrounding the chief ray are injected through the image injection surface, prior to entering the light guide, some of the light corresponding to the angular field is partially reflected by the partially reflective surface and some is partially transmitted by the partially reflective surface.

Description

Technical Field

[0001] The present disclosure relates to the field of near-eye display optical systems, such as head-mounted displays. More specifically, the present disclosure relates to reducing the size of near-eye display optical systems by employing beam splitters and coupling prism arrangements. Background Art

[0002] Consumer demand for improved human-machine interfaces has led to increased interest in high-quality image head-mounted displays (HMDs) or near-eye displays (NEDs), commonly referred to as smart glasses. These devices can provide virtual reality (VR) or augmented reality (AR) experiences, enhancing the way users interact with digital content and their surroundings.

[0003] Consumers seek better image quality, immersive experience, and greater comfort when using HMDs. They expect displays to have high resolution, vivid colors, and minimal distortion to create a realistic and enjoyable viewing experience. In addition, since users often wear these devices for long periods of time, comfort is a key factor. Consumers expect lightweight, sleek designs that are less obtrusive and more convenient to wear in various scenarios. Smaller devices also provide improved portability, making it easier to carry and use these devices in different environments. Therefore, there is a growing demand for higher performance but smaller and more compact HMDs.

[0004] The key element of a near-eye display system is the projector. In the case of HMDs and NEDs, the image projector is a device that generates visual content and projects it onto an intermediate medium (i.e., a light guide) for delivery to the eye. The goal is to provide the user with an image or video perception, often with an illusion of depth or three-dimensionality. In the realm of HMDs and NEDs, the size of the image projector can be influenced by the entrance pupil into the light guide. Ideally, for compactness and efficiency, both the entrance pupils of the projector and the light guide should be small.

[0005] The technologies behind projectors for HMDs and NEDs include LED, OLED, and Liquid Crystal on Silicon (LCoS). An increasingly popular projector technology involves laser projectors. Laser projectors in near-eye displays (NEDs) use laser light sources to generate and project images. Although laser projectors have several advantages such as high brightness, wide color gamut, compact structure, and low power consumption, there are also some challenges in their use, such as the easy generation of coherent interference patterns. Summary of the invention

[0006] In near-eye displays, the geometric relationship between the entrance pupil of the light guide and the size of the image projector is critical. The size of the entrance pupil directly affects the size of the projector, and a smaller entrance pupil is ideal for a more compact projector. In conventional light guides, the pupil size is approximately twice the thickness of the light guide. The present disclosure presents an enhanced optical system that reduces the pupil size by employing a beam splitter and a coupled prism arrangement.

[0007] The accompanying drawings that are incorporated in the specification and form a part of the specification illustrate various example systems, methods, etc., which illustrate various example implementations of various aspects of the present invention. It will be understood that the element boundaries (e.g., boxes, groups of boxes, or other shapes) shown in the figures represent an example of boundaries. It will be understood by those of ordinary skill in the art that an element can be designed as multiple elements, or multiple elements can be designed as one element. An element shown as an internal component of another element can be implemented as an external component, and conversely, an element shown as an external component of another element can be implemented as an internal component. In addition, elements may not be drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown.

[0009] Figure 2A , Figure 2B and Figure 2C Shows Figure 1 Schematic diagram of an optical system showing different angles of a light beam entering the optical system.

[0010] Figure 3 A schematic diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown.

[0011] Figure 4 An example process for manufacturing an optical system is shown.

[0012] Figure 5 A schematic diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown.

[0013] Figure 6 A schematic diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown.

[0014] Fig. 7A and Figure 7B A schematic diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown.

[0015] Figure 7C A schematic diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown.

[0016] Fig.7D and Fig. 7E Various alternative configurations of prisms and beam splitters disclosed are schematically shown.

[0017] Figure 8 A schematic diagram of an exemplary optical system incorporating two beam splitters and a coupling prism is shown.

[0018] Fig. 9 A schematic diagram of an exemplary optical system incorporating a coupling prism into which multiple beamsplitter surfaces are built is shown.

[0019] Fig. 10A and Fig. 10B A schematic diagram of an exemplary optical system incorporating a coupling prism and a beam splitter having multiple separation surfaces built therein is shown.

[0020] FIG. 11A to FIG. 11C A diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown.

[0021] FIG. 12A to FIG. 12D A prior art optical system is shown.

[0022] FIG. 13A to FIG. 13D A diagram of an exemplary optical system incorporating a beam splitter and coupling prism arrangement is shown. DETAILED DESCRIPTION

[0023] In near-eye displays, the geometric relationship between the entrance pupil of the light guide and the size of the image projector is critical. The size of the entrance pupil directly affects the size of the projector, and a smaller entrance pupil is ideal for a more compact projector. In conventional light guides, the pupil size is approximately twice the thickness of the light guide. The present disclosure presents an enhanced optical system that provides a reduced pupil size.

[0024] Figure 1 A schematic diagram of an exemplary optical system 1 is shown.

[0025] The system 1 includes a light-guide optical element (LOE) 10, which is generally formed of a transparent material. The LOE 10 has a first major outer surface 11a and a second major outer surface 11b, which are parallel to each other and are used to guide light in the LOE 10 by internal reflection. The LOE 10 may also include a light input end 11c, through which light enters the LOE 10.

[0026] The system 1 further comprises a beam splitter 17 disposed adjacent to the light input end 11c of the LOE 10. The beam splitter 17 has a partially reflective surface 17a which is parallel to the first major outer surface 11a and the second major outer surface 11b of the LOE 10. The beam splitter 17 also has an incoupling surface 17b through which light enters the beam splitter 17.

[0027] The system 1 also includes a projector 12 that projects light corresponding to an image (e.g., a collimated image) and has a beam width 12a, which is the beam width of a collimated light beam. For example, the projector 12 can be a laser projector. The light beam 12a has a chief ray 24 that defines the optical axis of the projector 12 and corresponds to a point in the image. The projected light also has an angular field around the chief ray 24 that corresponds to other points in the image. The system has an aperture 17c. All collimated light beams of the image pass through the aperture 17c. Aperture 17c is the exit aperture of the laser system and is also the entrance aperture of the waveguide 10. FIG. 2 below describes all fields at various angles passing through the aperture 17c. The size of the projector 12 is not drawn to scale.

[0028] The system 1 also includes a coupling prism 15 having an image injection surface 15a. The projector 12 projects light corresponding to the image to be injected into the prism 15 via the image injection surface 15a. The injected light beam (represented by the two extreme light beams 14a and 14b) impinges on the image injection surface 15a of the prism 15. The main light ray 24 impinges perpendicularly on the image injection surface 15a, thereby minimizing aberrations. Light rays corresponding to the angular field also enter the prism 15 via the image injection surface 15a. These lights travel through the prism 15 to the coupling surface 17b of the beam splitter 17.

[0029] The partially reflective surface 17a of the beam splitter 17 transmits a portion (e.g., 50%) and reflects a portion (e.g., 50%) of the light impinging on the partially reflective surface 17a, as described, for example, in PCT International Phase Application Publication No. WO2021001841A1. In the present embodiment, the partially reflective surface 17a is designed to have a length such that each ray of the shallowest angle light entering through the coupling-in surface 17b in the angular field strikes the partially reflective surface 17a of the beam splitter 17 exactly once before entering the LOE via the light input end 11c to propagate within the LOE 10 by internal reflection. The beam splitter 17 can effectively split the injected light by 1 / 2, doubling the illumination entering the LOE 10, thereby requiring a smaller projection optics to the light guide 10, reducing the size. Therefore, ideally, the partially reflective surface 17a is long enough so that each ray can strike the partially reflective surface 17a. However, if the partially reflective surface 17a is too long, the previously separated light may hit the partially reflective surface a second time and recombine, resulting in undesired interference. In system 1, light separated after hitting the surface 17a for the first time does not hit the surface a second time. In fact, the length of the partially reflective surface 17a of the beam splitter 17 is such that most of the light in the angular field that is transmitted through the coupling-in surface 17b will hit the partially reflective surface 17a exactly once before entering the LOE to propagate within the LOE by internal reflection. Therefore, the surface 17a acts as a beam splitter rather than a combiner. Therefore, coherent light can be injected into the light guide without the risk of generating a coherent interference pattern.

[0030] The system 1 may also include a light absorber 18 that trims excess light at one end of the range between 14a and 14b. The light absorber 18 is adjacent to a surface 17d of the beam splitter 17 opposite the coupling-in surface 17b. A trimming position 20 (corresponding to an end of the light absorber 18) is positioned directly opposite the angle 16 that trims excess light at the other end of the range between 14a and 14b. Thus, the angle 16 and the trimming position 20 perform symmetrical trimming of the transmitted beam. In effect, a virtual plane 17c is formed between the angle 16 and the position 20 that defines an entrance pupil into the LOE 10.

[0031] Figure 2A , Figure 2B and Figure 2C A schematic diagram of the optical system 1 is shown, which illustrates the different angles of all overlaps of the light beams entering the optical system 1 when passing through the surface 17c (the entrance aperture of the waveguide 10). Figure 2A The shallowest angle α relative to the first main surface 11a and the second main surface 11b is shown. Figure 2C shows the steepest angle γ with respect to the first major surface 11a and the second major surface 11b, and Figure 2BThe angle β between α and γ is shown. Here, with respect to the first major surface 11a and the second major surface 11b, α<β<γ. It is obvious from these figures that the optimal length of the partially reflecting surface 17a is different for different field angles. Figure 2A In , the length of the partially reflecting surface 17a is set to maximize the beam separation while minimizing the interference of the shallowest angles represented by the light rays 14a, 14b. Figure 2A In FIG. 1 , the overlap between the extreme rays 14a, 14b at 30a (i.e., the end of the partially reflecting surface 17a) is minimized. Figure 2B and Figure 2C In the embodiment of FIG. 1 , there is significant overlap between light rays 34a, 34b (at 30b and 30c) and between light rays 44a, 44b, which corresponds to an undesirable length of the partially reflective surface 17a for these steeper angles. In practice, the length of the surface 17a is a compromise: if it is too long, some interference is expected due to recombination at 30b and 30c. However, if the length of the partially reflective surface 17a is set too short, some illumination unevenness is expected due to lack of beam separation.

[0032] In determining the length of the partially reflecting surface 17a, a compromise may correspond to maximizing the beam separation to ensure uniform illumination while minimizing the interference generated by the recombination as much as possible. Figure 1 and Figure 2A As shown in Figure 1, this is equivalent to optimizing the light at the shallowest angle. With this goal in mind, Figure 1 As can be seen in FIG. 1 , a suitable length L of the partially reflective surface 17a can be approximately equal to half of the total internal reflection round trip of the light ray 14b. Therefore, the length L of the partially reflective surface 17a can be set to be approximately equal to the length L of the LOE 10, in which the light from the light ray 14b (i.e., the light of the most oblique (i.e., shallowest) angle in the angular field, which is farthest from the top side of the beam splitter 17 and enters through the coupling-in surface 17b) travels from the first major outer surface 11a to the second major outer surface 11b once when propagating in the LOE 11 by internal reflection.

[0033] This provided length L of the partially reflective surface 17a of the beam splitter 17 minimizes interference patterns caused by light corresponding to a point in the image striking the partially reflective surface 17a of the beam splitter 17 more than once before entering the LOE 10 while maximizing illumination of the LOE 10 .

[0034] Figure 3 Shown with Figure 1 The system is similar to system 1a, except that the coupling prism 35 is placed on top of the beam splitter 37, resulting in a simpler implementation at the expense of a larger projector 12.

[0035] The system 1a includes a LOE 10, the LOE 10 having a light input surface 11c and a first main outer surface 11a and a second main outer surface 11b parallel to each other, the first main outer surface 11a and the second main outer surface 11b being used to guide light in the LOE 10 by internal reflection, and the light enters the LOE 10 through the light input surface 11c. The system 1a also includes a beam splitter 37 disposed adjacent to the light input end 11c of the LOE 10. The beam splitter 37 has a partially reflective surface 37a, which is parallel to the first main outer surface 11a and the second main outer surface 11b of the LOE 10. The beam splitter 37 also has a coupling surface 37b, through which the light enters the beam splitter 37. The system 1a also includes a projector 12, which projects light corresponding to an image (e.g., a collimated image) and having a beam width 12a. The system 1a also includes a coupling prism 35, which has an image injection surface 35a.

[0036] The projector 12 projects light corresponding to the image to be injected into the prism 35 via the image injection surface 35a. The injected light beam (represented by the two extreme light beams 14a and 14b) impinges on the image injection surface 35a of the prism 35. The light travels through the prism 35 to the coupling-in surface 37b of the beam splitter 37. The partially reflective surface 37a of the beam splitter 37 transmits a portion (e.g., 50%) of the light impinging thereon and reflects a portion (e.g., 50%).

[0037] In this embodiment, the partially reflective surface 37a is designed to have a length such that each ray of the shallowest angle light in the angular field entering through the coupling-in surface 37b hits the partially reflective surface 37a of the beam splitter 37 exactly once before entering the LOE via the light input end 11c to propagate within the LOE 10 by internal reflection. The length of the partially reflective surface 37a of the beam splitter 37 is such that most of the light in the angular field transmitted through the coupling-in surface 37b hits the partially reflective surface 37a exactly once before entering the LOE to propagate within the LOE 10 by internal reflection. Therefore, the surface 37a acts as a beam splitter rather than a combiner. Therefore, coherent light can be injected into the light guide without the risk of generating a coherent interference pattern.

[0038] System 1a can also include a light absorber 38 that trims excess light at one end of the range between 14a and 14b. Light absorber 38 is adjacent to surface 37d of beam splitter 37 opposite coupling-in surface 37b. Trimming position 40 (corresponding to the end of light absorber 38) is positioned directly opposite angle 36, which trims excess light at the other end of the range between 14a and 14b. Thus, angle 36 and trimming position 40 perform symmetrical trimming of the transmitted light beam. In effect, a virtual plane is formed between angle 36 and position 40, defining an entrance pupil (also referred to herein as an aperture) into LOE 10.

[0039] exist Figure 1 In the system 1, the coupling surface 17b is at an oblique angle relative to the first main surface 11a and the second main surface 11b, and Figure 3 In the system 1a, the coupling surface 37b is parallel to the first main surface 11a and the second main surface 11b.

[0040] Figure 4 The process of manufacturing optical system 1 and optical system 1a is shown. The plates at step 40 are coated with partial reflectors and attached together at step 42 to form beam splitter 17. The attached plates forming beam splitter 17 can be attached to light guide 10 at step 44 to be polished together and produce a combined external facet. At step 46a, the corners of beam splitter 17 can be polished and prism 15 attached thereto. Alternatively, at step 46b, prism 35 can be attached directly to the light guide face of beam splitter 17 (now 37 because no corners have been removed).

[0041] At this stage, an absorbing coating may be applied to form light absorber 18 or light absorber 38 .

[0042] Further simplification of the beam splitting configuration can be achieved by implementing the partial reflector within the coupling prism, rather than as a separate component or part of the light guide 10. Figure 5 and Figure 6 shown.

[0043] exist Figure 5 In system 1b of FIG. 1 , partial reflector 57 is contained within prism 55 so that it can be made as a single element to be attached to light guide 10. In this configuration, light beam 12 enters through surface 55a and directly impinges on the aperture between 56 and 70. Here, arrow 86 represents the direct beam (without separation), so the partial illumination will have twice the intensity, while segment 88 shows the area where no light passes (as shown by the lack of light outside the illuminator aperture 12 as indicated by the dashed arrow 87). Therefore, in this configuration, the uniformity of the illumination will be reduced. However, in some applications, this non-uniformity can be tolerated.

[0044] A light absorber 58 may be disposed adjacent to a second side 55 b of the prism 55 opposite the input side 55 a .

[0045] Figure 6 Shown with Figure 5 Equivalent construction 1c, except that the illumination is located at the lower part of the aperture and the bottom surface 65b of the prism 65 is reflective. The partial reflector 67 is contained in the prism 65, so it can be made as a single element and attached to the light guide 10. In this construction, the light beam 12 enters through the surface 65a and directly illuminates the aperture between 66 and 70. Here, the arrow 86 represents the (unsplit) direct beam, so the partial illumination will have twice the intensity, and the segment 88 shows the area where no light passes (lack of light). Therefore, in this construction, the uniformity of the illumination will be reduced. However, in some applications, this non-uniformity can be tolerated.

[0046] Fig. 7A A further simplified construction 1d is shown, in which the coupling construction is limited to the width of the LOE 10. The light beams 14a, 14b enter the optical system 1d through a blank prism 50, which has a vertical incidence surface 51 for minimizing aberrations. The exit of the prism 50 and the entrance of the LOE 10 serve as an entrance pupil 52. The projection optics can be designed so that the exit aperture overlaps the light guide incident aperture 52. The aperture 52 is positioned very close to the incident surface 51, thereby realizing a small projection optics. Stray light at the entrance is cut off by optional absorption surfaces 54a and absorption surfaces 54b. In the first section of the LOE 10, the light beam hits once on the partial reflector surface 37a, resulting in uniform illumination of the LOE 10.

[0047] Figure 7B Two central beams 24a, 24b are shown at different angles (fields), where the dashed arrow 24a represents the shallowest beam in the image and the dashed arrow 24b represents the steepest beam in the image. At least a portion of the steepest beam 24b hits the partial reflector 37a twice. The additional length of the surface 37a is marked as 76. Therefore, when coherent illumination is used, interference patterns may appear in a portion of the field of the projected image. Figure 1 As mentioned above, the length of 37a can be set shorter, but the illumination uniformity at the edge of the field will be partially damaged.

[0048] exist Figure 1 In the system 1, the coupling surface 17b is at an oblique angle relative to the first main surface 11a and the second main surface 11b. Figure 3 In the system 1a, the coupling surface 37b is parallel to the first main surface 11a and the second main surface 11b, and Fig. 7A and Figure 7B In the system 1d, the coupling surface 52 is perpendicular to the first main surface and the second main surface.

[0049] As shown, the optional absorber 54a may be positioned so that its ends do not clip the steepest rays.

[0050] Figure 7C An equivalent configuration 1e is shown in which the transparent incident prism is replaced by a reflecting prism 70 having a reflector 78. Further optical components (not shown) may be added to suppress aberrations. The coupling surface 52 is perpendicular to the first and second major surfaces. The reflecting surface 78 may be attached to the coupling prism 70, coated on the coupling prism 70, or form a part of the coupling prism 70 so that the light 12 injected through the image injection surface 70a is reflected by the reflecting surface 78 toward the coupling surface 52. In some embodiments, the reflecting prism 70 may be larger than the width of the light guide 10.

[0051] In the case of a rectangular cross-section light guide, the transparent prism 50, reflector 70 and all prisms described above may be tilted out of the plane of the illustration to inject light in the proper orientation.

[0052] Fig.7D A front view of an implementation of a rectangular light guide is schematically shown, wherein the beam splitter 37 is oriented laterally as described above.

[0053] Fig. 7E There is shown another implementation of the vertical beam splitter 60 in addition to the beam splitter 37. The vertical beam splitter 60 may be implemented in the transparent prism 50 or in the reflecting prism 70. Alternatively, it may be implemented in various beam splitters 17, 37, etc. in the above-mentioned configurations.

[0054] A beam splitter implemented using multiple partial reflectors can further improve the performance of the system in terms of projector size, uniformity, and coupling segment size. Figure 8 , Fig. 9 and Figure 10 shows a system incorporating multiple partial reflectors.

[0055] Figure 8 A system 1f is shown in which the beam splitter 97 includes two partial reflectors 97a, 97b for reducing the input aperture 97c. In one embodiment, the reflectivity of the partial reflector 97a is 33% and the reflectivity of the partial reflector 97b is 50%. In other embodiments, the reflectivities of the partial reflectors 97a and 97b may be different from 33% and 50%, respectively. Figure 8 In the embodiment of the present invention, the partial reflector 97a has the same length as the partial reflector 97b, but is shifted to the left relative to the partial reflector 97b. Figure 1 As in the case of a single partial reflector, the entrance pupil 97c is now smaller.

[0056] The location and reflectivity of the partial reflectors 97a, 97b may be selected to ensure uniform illumination of the light guide 10 at a nominal illumination angle. Light absorbers 98a, 98b may be used to absorb stray light. The absorbers 98a, 98b may be implemented simultaneously, individually, or not at all.

[0057] Advantages of system 1f having a reduced size aperture 97c may include the ability to use a smaller size prism 95 and / or a smaller size projector 12.

[0058] Fig. 9 A system 1g is shown, which includes a prism 105 including three partial reflectors 107a, 107b and 107d contained therein to improve the Figure 5 Light uniformity in an equivalent simplified configuration. Light absorbers 108a, 108b, and 108c may be used to attenuate stray light. Various reflectivity values ​​may be defined for partial reflectors 107a, 107b, and 107d. In one embodiment, the reflectivity of partial reflector 107a is lower than that of partial reflector 107d, while the reflectivity of partial reflector 107b is between partial reflectors 107a and 107d.

[0059] In this configuration, an input aperture 107c may be defined. Reflections from the partial reflectors 107a, 107b, 107d are used to displace the illumination to fill the light guide 10. In this configuration, the light beam 12 enters through the prism 105 and impinges directly on the aperture 107c.

[0060] In system 1g, with Figure 5 and Figure 6 Compared to the illumination of the system shown in FIG. 1 , the output illumination on the light guide 10 is more uniform. Here, all segments are illuminated uniformly. Figure 5 and Figure 6 A blank segment 88 is shown, as well as a fully illuminated segment 86 .

[0061] Fig. 10A A system 1h is shown, which includes a beam splitter 117, which includes two partial reflectors 117a, 117b, which are constructed similar to Fig. 7A Similar to Fig. 7AThe additional beam splitting produced by the additional partial reflector 117b reduces the length of the beam splitter 117 and the partial reflectors 117a, 117b compared to the configuration of FIG. 1 . The light beams 14a, 14b enter the optical system 1h through a blank prism 50 having a vertical incident surface 51, which is used to minimize aberrations. The exit of the prism 50 and the entrance of the LOE 10 serve as an entrance pupil 52. The projection optics can be designed so that the exit aperture overlaps the light guide incident aperture 52. The aperture 52 is positioned very close to the incident surface 51, thereby achieving a compact projection optics. Stray light is cut off at the entrance by optional absorption surfaces 54a and 54b. The light beams hit the partial reflectors 107a, 107b once, resulting in uniform illumination of the LOE 10.

[0062] Fig. 10B It is schematically shown that the beam splitter 117 may include vertical partial reflectors 120a, 120b in addition to the horizontal partial reflectors 117a, 117b.

[0063] Fig.11A and Fig. 11B An implementation of a single prism is shown, which can be used both as a reflector (primarily for ergonomic reasons) and as a single reflective beam splitter.

[0064] Fig.11A The reflectivity curve of the dielectric coating is graphically shown, with the dielectric coating having a minimum reflectivity at a low angle 118 and a reflectivity of 50% at a high angle 120. Fig. 11B In the illustrated construction, the coating is implemented as a separation surface 122 of the system 1i. An impinging light beam having a width 12 (boundary marked by a dashed arrow) enters the prism 124 at a low angle (within 118). A portion of the light beam 12 impinges on the separation surface 122 and therefore passes through the separation surface 122 with minimal loss. This portion of the light beam is reflected by the segment 126 of the planar reflector 128 onto the light guide 10 (large solid arrow). The light that does not pass through the beam splitter 122 strikes the planar reflector 128 at the segment 130 and is reflected at the same angle. These lights are marked as dashed thick arrows. The reflections (solid and dashed arrows) are identical and continuous. For clarity of description, they are separated here.

[0065] The illumination from the segment 126 impinges on the beam splitter 122 at a high angle 120 and is thus split as shown. The reflection from the segment 130 is first reflected from the end of the prism 124 (which may also be referred to as the face of the light guide 10) and then impinges on the end of the separation surface 122 at a high angle 120 and is thus also split in two as shown. By appropriately choosing the width of the reflector 128 and the length of the beam splitter 122, a uniform and complete illumination of the light guide 10 can be achieved. The fact that a single prism 124 comprises the beam splitter 122 and the reflector 128 (and, if desired, the continuation of the top and bottom reflectors and the external face of the light guide 10) allows a simple and low-cost manufacture of the folding and separation device.

[0066] Fig. 11C A system 1j is shown, wherein Fig. 11B The reflectors 128 in the optics are placed anywhere along the same plane. The illumination 12 strikes all reflectors 128, so the output will be uniform, only the relative widths of 126 and 130 will vary. In this figure, the reflectors 128 are moved to the lowest position (optimal for reducing the size of the optics and simplifying production), so the illumination from 126 is less than that from 130. This configuration can include more beam splitters, making the incident beam 12 and the optics narrower.

[0067] In a further embodiment, the two-dimensional light guide comprises two sets of parallel faces that are perpendicular to each other. Incoupling into these rectangular cross-section light guides is described in US 10,564,417. FIG. 12A to FIG. 12D Various coupling configurations based on refraction and reflection of optical devices disclosed in the '417 patent are shown. The coupling device includes trimmed edges: 16a and 16b. Figure 1 to Figure 1 The beam splitting configurations described in 1 can be combined to produce optimal coupling of light into such a 2D light guide. The aperture can be reduced in one or both dimensions.

[0068] Fig.13A , Fig. 13B and Fig. 13C The reflecting prism 134 is combined with Figure 1 10. The light (beams 14a-14d) enter the prism 134 and are reflected by the reflective surface 131a onto the light guide 10. The entrance aperture is defined in one dimension by 16a and in another dimension by 16b. The partial reflector 17 enables the aperture to be reduced vertically (e.g., Figure 1 ), and also allows the prism 134 to include (having Fig.11A The partial reflector 122 of the curve, such as Fig. 11B as stated (or as Fig. 9as described above, but here it is a reflecting prism).

[0069] Fig.13D A simplified configuration is shown in which the reflective prism 134 is attached directly to the light guide 10 without the prism 15 .

[0070] like Fig. 10B As shown, in all of the above configurations, beam splitting can be achieved by crossed partial reflectors, while the separate method described in Figure 13 simplifies the production process by using the beam splitter as a separate component.

[0071] The absorbers described in the above configurations may be replaced by prisms or other refractive components that couple light out of the corresponding system.

[0072] definition

[0073] Included below are definitions of selected terms used herein. The definitions include various examples or forms of components that fall within the scope of the terms and can be used in implementations. The examples are not intended to be limiting. Both singular and plural forms of the terms may be within the definitions.

[0074] An "operable connection" or a connection through which entities are "operably connected" is a connection in which signals, physical communications, or logical communications can be sent or received. Typically, an operable connection includes a physical interface, an electrical interface, or a data interface, but it should be noted that an operable connection may include different combinations of these or other types of connections sufficient to allow operable control. For example, two entities may be operably connected by being able to transmit signals to each other directly or through one or more intermediate entities (such as a processor, operating system, logic, software, or other entity). Logical or physical communication channels may be used to create an operable connection.

[0075] To the extent that the terms "includes" or "including" are employed in the detailed description or the claims, they are intended to be inclusive in a manner similar to the way the term "comprising" is interpreted when used as a transition word in the claims. In addition, to the extent that the term "or" is employed in the detailed description or the claims (e.g., A or B), it is intended to mean "A or B or both." When applicants intend to indicate "only A or B but not both," then the term "only A or B but not both" will be used. Thus, the use of the term "or" herein is inclusive, rather than exclusive. See Bryan A. Garner, Dictionary of Contemporary Legal Usage, 624 (2d. Ed. 1995).

[0076] Although example systems, methods, etc. have been shown by describing examples, and although examples have been described in considerable detail, it is not the intention of the applicant to limit or in any way restrict the scope to such details. Of course, in order to describe the systems, methods, etc. described herein, it is impossible to describe every conceivable combination of components or methods. Additional advantages and modifications will be apparent to those skilled in the art. Therefore, the present invention is not limited to the specific details, representative devices, and illustrative examples shown and described. Therefore, the present application is intended to include changes, modifications, and variations that fall within the scope of the appended claims. In addition, the previous description is not intended to limit the scope of the present invention. On the contrary, the scope of the present invention is determined by the appended claims and their equivalents.

Claims

1. An optical system, comprising: a light guide optical element (LOE) formed of a transparent material and having a light input end and a mutually parallel first and second major outer surfaces for guiding light by internal reflection; A beam splitter disposed adjacent to the light input end and having a partially reflective surface and an incoupling surface parallel to the first main outer surface and the second main outer surface; a projector configured to project light corresponding to a collimated image from an aperture, the light exiting the aperture with a principal ray defining an optical axis of the projector and with an angular field about the principal ray; as well as a coupling prism adjacent to the coupling-in surface, the coupling prism having an image injection surface, the projector being associated with the image injection surface and oriented such that at least some of the chief ray and the angular field surrounding the chief ray are injected through the image injection surface and travel to the coupling-in surface, The length dimension of the partially reflective surface of the beam splitter is such that, for each light ray at the shallowest angle relative to the first main outer surface and the second main outer surface, the light entering through the coupling-in surface in the angular field hits the partially reflective surface of the beam splitter exactly once before entering the LOE to propagate within the LOE by internal reflection.

2. The optical system according to claim 1, comprising: A light absorber is disposed adjacent to a second surface of the beam splitter opposite the coupling-in surface, an end of the light absorber and an end of the coupling-in surface defining an entrance pupil into the LOE.

3. The optical system according to claim 1, wherein: The coupling-in surface is one of: At an oblique angle relative to the first major surface and the second major surface, parallel to the first major surface and the second major surface, and perpendicular to the first major surface and the second major surface.

4. The optical system according to claim 1, wherein: The coupling-in surface is perpendicular to the first main surface and the second main surface, and the optical system further comprises: A reflective surface is attached to the coupling prism or forms a part of the coupling prism, such that light injected through the image injection surface is reflected by the reflective surface towards the coupling-in surface.

5. The optical system according to claim 1, wherein: The partially reflective surface of the beam splitter has a length dimension that minimizes interference patterns caused by light corresponding to a point in the image striking the partially reflective surface of the beam splitter more than once before entering the LOE.

6. The optical system according to claim 1, wherein: The beam splitter includes a second partially reflective surface parallel to the first major outer surface and the second major outer surface.

7. The optical system according to claim 1, wherein: The beam splitter includes a second partially reflective surface parallel to the first major outer surface and the second major outer surface, the second partially reflective surface being disposed closer to the LOE than the first partially reflective surface.

8. The optical system according to claim 1, wherein: One or more partially reflective surfaces perpendicular to the first main outer surface and the second main outer surface are built into the coupling prism or the second coupling prism.

9. An optical system comprising: a light guide optical element (LOE) formed of a transparent material and having a light input end and a mutually parallel first and second major outer surfaces for guiding light by internal reflection; a beam splitter disposed adjacent to the light input end and having a partially reflective surface parallel to the first and second main outer surfaces and an incoupling surface on the input side; a projector configured to project light corresponding to an image from an aperture, the light exiting the aperture with a principal ray defining an optical axis of the projector and with an angular field about the principal ray; as well as a coupling prism adjacent the coupling-in surface, the coupling prism having an image injection surface at an oblique angle relative to the first and second major outer surfaces, the projector being associated with the image injection surface and oriented such that at least some of the principal ray and the angular field surrounding the principal ray are injected through the image injection surface, The length dimension of the partially reflective surface of the beam splitter is approximately equal to the length of the LOE, and in the LOE, the light in the light ray with the largest inclination angle relative to the first main outer surface and the second main outer surface, and the light farthest from the input side in the angular field that enters through the coupling-in surface travels from the first main outer surface to the second main outer surface once when propagating in the LOE by internal reflection.

10. The optical system according to claim 9, comprising: a light absorber disposed adjacent a second side of the beam splitter opposite the input side; A virtual plane, which is perpendicular to the first major surface and the second major surface and intersects the end of the coupling surface and a position adjacent to the end of the light absorber on the second side, correspondingly defines an entrance pupil into the LOE.

11. The optical system according to claim 9, wherein: The coupling-in surface is one of: At an oblique angle relative to the first major surface and the second major surface, parallel to the first major surface and the second major surface, and perpendicular to the first major surface and the second major surface.

12. The optical system according to claim 9, wherein: The coupling-in surface is perpendicular to the first main surface and the second main surface, and the optical system further comprises: A reflective surface is attached to the coupling prism or forms a part of the coupling prism, such that light injected through the image injection surface is reflected by the reflective surface towards the coupling-in surface.

13. The optical system according to claim 9, wherein: The partially reflective surface of the beam splitter has a length dimension that minimizes interference patterns caused by light corresponding to a point in the image striking the partially reflective surface of the beam splitter more than once before entering the LOE.

14. The optical system according to claim 9, wherein: The beam splitter includes a second partially reflective surface parallel to the first major outer surface and the second major outer surface.

15. The optical system according to claim 9, wherein: The beam splitter includes a second partially reflective surface parallel to the first major outer surface and the second major outer surface, the second partially reflective surface being disposed closer to the LOE than the first partially reflective surface.

16. The optical system according to claim 9, wherein: One or more partially reflective surfaces perpendicular to the first main outer surface and the second main outer surface are built into the coupling prism or the second coupling prism.

17. An optical system comprising: a light guide optical element (LOE) having a light input end and a mutually parallel first and second major outer surfaces for guiding light by internal reflection; A beam splitter disposed adjacent to the light input end and having a partially reflective surface and an incoupling surface parallel to the first main outer surface and the second main outer surface; a laser projector configured to project light corresponding to an image from an aperture, the light exiting the aperture in a principal ray defining an optical axis of the laser projector and in an angular field about the principal ray; as well as a coupling prism adjacent to the coupling-in surface, the coupling prism having an image injection surface, the laser projector being associated with the image injection surface and oriented so that at least some of the chief ray and the angular field surrounding the chief ray are injected through the image injection surface, The length dimension of the partially reflective surface of the beam splitter is such that most of the light in the angular field transmitted through the coupling-in surface hits the partially reflective surface of the beam splitter exactly once before entering the LOE to propagate within the LOE by internal reflection.

18. An optical system according to claim 17, comprising: A light absorber is disposed adjacent to a second surface of the beam splitter opposite to the coupling-in surface, an end of the light absorber and a corner of the coupling prism adjacent to the coupling-in surface defining an entrance pupil into the LOE.

19. The optical system of claim 17, wherein: The coupling-in surface is one of: At an oblique angle relative to the first major surface and the second major surface, parallel to the first major surface and the second major surface, and perpendicular to the first major surface and the second major surface.

20. The optical system of claim 17, wherein: The coupling-in surface is perpendicular to the first main surface and the second main surface, and the optical system further comprises: A reflective surface is attached to the coupling prism or forms a part of the coupling prism, such that light injected through the image injection surface is reflected by the reflective surface towards the coupling-in surface.

21. The optical system of claim 17, wherein: The partially reflective surface of the beam splitter has a length dimension that minimizes interference patterns caused by light corresponding to a point in the image striking the partially reflective surface of the beam splitter more than once before entering the LOE.

22. The optical system of claim 17, the beam splitter having a second partially reflective surface perpendicular to the first and second major outer surfaces.

23. The optical system of claim 17, wherein: The beam splitter includes a second partially reflective surface parallel to the first major outer surface and the second major outer surface.

24. The optical system of claim 17, wherein: The beam splitter includes a second partially reflective surface parallel to the first major outer surface and the second major outer surface, the second partially reflective surface being disposed closer to the LOE than the first partially reflective surface.

25. The optical system of claim 17, wherein: One or more partially reflective surfaces perpendicular to the first main outer surface and the second main outer surface are built into the coupling prism or the second coupling prism.

26. The optical system of claim 17, comprising a second prism adjacent to the coupling prism, the second prism having one or more partially reflective surfaces built therein that are perpendicular to the first major outer surface and the second major outer surface.

27. An optical system comprising: a light guide optical element (LOE) having a light input end and a mutually parallel first and second major outer surfaces for guiding light by internal reflection; a projector configured to project light corresponding to an image from an aperture, the light exiting the aperture with a principal ray defining an optical axis of the projector and with an angular field about the principal ray; as well as A prism is arranged adjacent to the light input end and has a partially reflective surface parallel to the first main outer surface and the second main outer surface and an image injection surface, the projector is associated with the image injection surface and is oriented so that at least some of the main light and the angular field surrounding the main light are injected through the image injection surface, and some of the light corresponding to the angular field is partially reflected by the partially reflective surface and some is partially transmitted by the partially reflective surface before entering the LOE.

28. The optical system of claim 27, comprising: A light absorber is disposed adjacent to the bottom surface of the prism, and an end of the light absorber is adjacent to the light input end.

29. The optical system of claim 27, wherein: The prism has a reflective bottom surface, and the projector is configured so that a majority of the light injected through the image injection surface impinges on the partially reflective surface exactly once.

30. The optical system of claim 27, wherein: The partially reflective surface has a length dimension that minimizes interference patterns caused by light corresponding to a point in the image striking the partially reflective surface more than once before entering the LOE.

31. The optical system of claim 27, wherein: The prism includes a second partially reflective surface parallel to the first major outer surface and the second major outer surface.

32. The optical system of claim 27, wherein: The prism includes a second partially reflective surface and a third partially reflective surface parallel to the first major outer surface and the second major outer surface.

33. The optical system of claim 27, wherein: applying a dielectric coating on the partially reflective surface, the dielectric coating having different reflectivities for (a) light impinging thereon at a low angle relative to the partially reflective surface and (b) light impinging thereon at a high angle relative to the partially reflective surface, the reflectivity at the high angle relative to the partially reflective surface being greater than the reflectivity at the low angle relative to the partially reflective surface, The system comprises: a reflective surface attached to the coupling prism or forming a part of the coupling prism and arranged relative to the partially reflective surface so that a portion of the light injected through the image injection surface first passes through the partially reflective surface and is then reflected by the reflective surface toward the partially reflective surface, and a portion of the light injected through the image injection surface that does not first pass through the partially reflective surface is reflected by the reflective surface toward the second main outer surface.

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