Reflective facet waveguide with stacked facet layers

Abstract

A waveguide includes a plurality of reflective facet sets. Each of the plurality of reflective facet groups includes a first reflective facet for reflecting light having a first optical characteristic and a second reflective facet for reflecting light having a second optical characteristic different from the first optical characteristic. A first reflective facet in a first reflective facet group of the plurality of reflective facet groups overlaps a first reflective facet in a second group of the plurality of reflective facet groups.

Description

BACKGROUND OF THE INVENTION

[0001] In an eye-wearable display, display light beams from a light engine are initially coupled into a waveguide by an input coupler, which may be formed on one or more surfaces of the waveguide or disposed within the waveguide. Once the display light beams have been coupled into the waveguide, the input-coupled display light beams are typically "guided" through the waveguide by multiple instances of total internal reflection (TIR) to then be directed out of the waveguide by an output coupler, which may also be formed on or within the waveguide. The output-coupled display light beams overlap at an appropriate eye distance from the waveguide to form an exit pupil, within which a virtual image generated by the light engine can be viewed by a user of the eye-wearable display. The waveguide may also include an exit pupil expander positioned between the input coupler and the output coupler to increase the size of the exit pupil within which the user can view the virtual image.

[0002] In some cases, one or more of the input coupler, the exit pupil expander, and the output coupler are implemented as a set of reflective facets within the waveguide. Conventional waveguides having reflective facets are often susceptible to degraded optical performance due to discontinuities in the virtual images delivered to the user. SUMMARY OF THE INVENTION

[0003] Various embodiments include waveguides having multiple sets of overlapping reflective facets that reduce or eliminate discontinuities in the light output-coupled from the waveguide.

[0004] In a first embodiment, a waveguide includes a plurality of sets of reflective facets. Each set of reflective facets of the plurality of sets of reflective facets includes a first reflective facet for reflecting light having a first optical characteristic and a second reflective facet for reflecting light having a second optical characteristic different from the first optical characteristic. The first reflective facet of the first set of reflective facets of the plurality of sets of reflective facets overlaps the first reflective facet of a second set of the plurality of sets of reflective facets.

[0005] In some aspects of the first embodiment, the second reflective facet in the first reflective facet group overlaps with the second reflective facet in the second reflective facet group. In some aspects, the first optical property is a first wavelength range, and the second optical property is a second wavelength range. For example, in some cases, the first wavelength range corresponds to blue light, and the second wavelength range corresponds to red light. In some aspects, the third reflective facet in the first reflective facet group overlaps with the third reflective facet in the second reflective facet group. The third reflective facet in each corresponding reflective facet group reflects light having a third optical property different from the first optical property and the second optical property. For example, the third optical property is a third wavelength range. In some cases, the first wavelength range corresponds to blue light, the second wavelength range corresponds to green light, and the third wavelength range corresponds to red light.

[0006] In some aspects of the first embodiment, the first optical property is a first polarization state, and the second optical property is a second polarization state.

[0007] In some aspects of the first embodiment, the first reflective facet in each reflective facet group transmits light having the second optical property.

[0008] In some aspects of the first embodiment, a plurality of reflective facet groups are included in an output coupler in a waveguide. In some aspects, the plurality of reflective facet groups are additionally or alternatively included in an input coupler or an exit pupil expander in the waveguide.

[0009] In a second embodiment, a waveguide includes a first reflective facet group and a second reflective facet group. Each reflective facet in the first reflective facet group is configured to reflect light having a specific wavelength range different from other reflective facets in the first reflective facet group, and each reflective facet in the second reflective facet group is configured to reflect light having a specific wavelength range different from other reflective facets in the second reflective facet group. Reflective facets in the first reflective facet group and the second reflective facet group that reflect similar wavelength ranges overlap with each other in the reflection direction.

[0010] In some aspects of the second embodiment, the first reflective facet group includes a first reflective facet that reflects light in a first wavelength range, a second reflective facet that reflects light in a second wavelength range, and a third reflective facet that reflects light in a third wavelength range. In some aspects, the first reflective facet transmits light in the second wavelength range and the third wavelength range, and the second reflective facet transmits light in the third wavelength range. In some aspects, the second reflective facet group similarly includes a first reflective facet that reflects light in a first wavelength range, a second reflective facet that reflects light in a second wavelength range, and a third reflective facet that reflects light in a third wavelength range. In some aspects, each reflective facet in the corresponding reflective facet group is separated from other reflective facets in the corresponding reflective facet group by a carrier layer. In some aspects, the first reflective facet group is separated from the second reflective facet group by a spacer layer. For example, in some cases, the spacer layer is thicker than the carrier layer that separates the reflective facets in the corresponding reflective facet group. In some cases, the first reflective facet group and the second reflective facet group are included in an output coupler in a waveguide.

[0011] In a third embodiment, a method for output-coupling light from a waveguide includes output-coupling light having a first wavelength range via a first reflective facet in a first reflective facet group and output-coupling light having a second wavelength range via a second reflective facet in the first reflective facet group, and output-coupling light having a first wavelength range via a first reflective facet in a second reflective facet group and output-coupling light having a second wavelength range via a second reflective facet in the second reflective facet group. In some cases, the first reflective facet in the first reflective facet group overlaps with the first reflective facet in the second reflective facet group in the output-coupling direction, and the second reflective facet in the first reflective facet group overlaps with the second reflective facet in the second reflective facet group in the output-coupling direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present disclosure can be better understood by reference to the accompanying drawings, and numerous features and advantages of the present disclosure will be apparent to those skilled in the art. The same reference numerals are used in different drawings to indicate similar or identical items.

[0013] Figure 1 An example eye-wearable display according to some embodiments is shown.

[0014] Figure 2 An example of a projection system having a filter between an optical engine and an input coupler of a waveguide of an eye-wearable display arranged in an eye-wearable display such as shown in Figure 1 is shown.

[0015] Figure 3 An example illustrating light in Figure 2Planar view of an example of propagation within a waveguide of a projection system.

[0016] Figure 4 Shows an example of a conventional reflective facet configuration and problems associated with such configurations.

[0017] Figure 5 Shows a cross-sectional view of a component for fabricating a stack of a set of reflective facets in a waveguide according to some embodiments.

[0018] Figure 6 Shows, according to various embodiments, Figure 5 A cross-sectional view of the components of the stack shown in together.

[0019] Figure 7 Shows, according to some embodiments, including Figure 6 A cross-sectional view of a final stacked stack of multiple stacked stacks shown in.

[0020] Figure 8 Shows, according to some embodiments, of Figure 7 A cross-sectional view of a cut made to the final stacked stack of.

[0021] Figure 9 Shows, according to some embodiments, having multiple reflective facets produced by a cut made as shown in Figure 8 An optical component segment.

[0022] Figure 10 And Figure 11 Shows, according to some embodiments, an example of surface treatment performed on an optical component segment of Figure 9 The optical component segment.

[0023] Figure 12 And Figure 13 Shows, according to some embodiments, integrating optical component segments such as those shown in Figures 9 to 11 Into a final waveguide such as those shown in Figure 2 And Figure 3 An example in the waveguide shown in.

[0024] Figure 14 Shows a flowchart depicting a method for output coupling light via an output coupler having overlapping multiple sets of reflective facets according to some embodiments. Detailed Description

[0025] The reflective facet waveguide includes one or more sets of reflective facets for implementing one or more of an input coupler, an output coupler, or an exit pupil expander. Using the output coupler as an example, the output coupler is implemented as a set of reflective facets that receive light from the exit pupil expander and reflect the light out of the waveguide towards the user. Typically, the set of reflective facets is made by applying a reflective coating to a series of flat surfaces on a molded plastic or polymer substrate. Ideally, each reflective facet has sharp corners at both sides and there are no gaps between adjacent reflective facets. However, in practice, due to molding process limitations, conventional molded plastic substrates have flat surfaces with rounded edges and draft angles (i.e., non-vertical angles) between the flat surfaces. These rounded edges and draft angles result in gaps between adjacent conventional reflective facets applied to the flat surfaces. The gaps between adjacent conventional reflective facets create gaps in the output-coupled light, which in turn create discontinuities in the virtual image delivered to the user. For example, if the virtual image is supposed to be a straight line, the gaps in the output-coupled light create "blips" in the line perceived by the user. Waveguides with overlapping stacked reflective facets are described herein that eliminate the discontinuities in the light output-coupled from the waveguide, thereby improving the optical performance of the waveguide and the eye-wearable display.

[0026] For illustration, in some embodiments, the waveguide includes an input coupler, an exit pupil expander, and an output coupler. At least one of these waveguide components—such as the output coupler—is embodied as multiple sets of reflective facets in the waveguide. Each set of reflective facets in the multiple sets of reflective facets has multiple reflective facets, and each reflective facet reflects light with specific optical properties in the output-coupling direction. For example, in some embodiments, each set of reflective facets has a first reflective facet that reflects blue light in the output-coupling direction, a second set of reflective facets that reflects green light in the output-coupling direction, and a third reflective facet that reflects red light in the output-coupling direction. Additionally, in some embodiments, the first reflective facet transmits green and red light, the second reflective facet transmits red and blue light, and the third reflective facet transmits green and blue light. Additionally, the first, second, and third reflective facets in each set of reflective facets overlap with the corresponding first, second, and third reflective facets in adjacent sets of reflective facets. In this way, the overlapping multiple sets of reflective facets eliminate the gaps in the light output-coupled from the waveguide, thereby improving the quality of the image perceived by the user.

[0027] Figure 1FIG. 0 shows an example ocular wearable display 100 in accordance with various embodiments. The ocular wearable display 100 (also referred to as a wearable head-up display (WHUD), a head-mounted display (HMD), a near-eye display, etc.) has a support structure 102 including an arm 104 that houses a microdisplay projection system configured to project an image toward a user's eye such that the user perceives the projected image as being displayed in a field-of-view (FOV) region 106 of a display at one or both of lens elements 108, 110. In the depicted embodiment, the support structure 102 of the ocular wearable display 100 is configured to be worn on a user's head and has the general shape and appearance of a pair of eyeglasses (i.e., “form factor”). The support structure 102 contains or otherwise includes various components for facilitating the projection of such images toward the user's eye, such as an optical engine and waveguides (e.g., as Figure 2 shown). In some embodiments, the support structure 102 further includes various sensors, such as one or more front cameras, rear cameras, other light sensors, motion sensors, accelerometers, etc. The support structure 102 may further include one or more radio frequency (RF) interfaces or other wireless interfaces, such as a Bluetooth™ interface, a WiFi interface, etc. Further, in some embodiments, the support structure 102 includes one or more batteries or other portable power sources for supplying power to the electrical components of the ocular wearable display 100. In some embodiments, some or all of these components of the ocular wearable display 100 are fully or partially contained within the interior volume of the support structure 102, such as within the arm 104 in the region 112 of the support structure 102. It should be noted that while an example form factor is depicted, it should be understood that in other embodiments, the ocular wearable display 100 may have a different shape and appearance than the Figure 1 pair of eyeglasses depicted.

[0028] The eye - worn display 100 uses one or both of the lens elements 108, 110 to provide an augmented reality (AR) or mixed reality (MR) display, in which the rendered graphical content can be superimposed on the real - world view perceived by the user through the lens elements 108, 110 or otherwise combined with the real - world view. In some embodiments, one or both of the lens elements 108, 110 function as an optical combiner that combines ambient light (also referred to as surrounding light) from outside the eye - worn display 100 and light emitted from the light engine in the eye - worn display 100. For example, the light used to form a perceivable image or series of images can be projected by the light engine of the eye - worn display 100 onto the user's eyes via a series of optical elements such as waveguides that are at least partially formed in the corresponding lens elements, one or more scanning mirrors, one or more optical relays, and / or one or more prisms. Thus, one or both of the lens elements 108, 110 include at least a portion of a waveguide that guides display light received by an input coupler of the waveguide to an output coupler of the waveguide, and the output coupler outputs the display light toward the eyes of the user of the eye - worn display 100. The display light is modulated and projected onto the user's eyes such that the user perceives the display light as an image in the FOV region 106. Additionally, in some embodiments, each of the lens elements 108, 110 is transparent enough to allow the user to look through the lens element to provide a field of view of the user's real - world environment, such that the image appears to be superimposed on at least a portion of the real - world environment.

[0029] In some embodiments, the light engine is any combination of a matrix-based projector, a scanning laser projector, or a modulated light source such as a laser or one or more LEDs and a dynamic reflector mechanism such as one or more dynamic scanners or a digital light processor. In some embodiments, for example, the light engine includes a plurality of laser diodes (e.g., a red laser diode, a green laser diode, and / or a blue laser diode) and at least one scanning mirror (e.g., two one-dimensional scanning mirrors that are microelectromechanical systems (MEMS)-based or piezoelectric-based). The light engine is communicatively coupled to a controller and a non-transitory processor-readable storage medium or memory that stores processor-executable instructions and other data, the processor-executable instructions and other data that, when executed by the controller, cause the controller to control the operation of the projector. In some embodiments, the controller controls the size and position of the scanning area of the light engine and is communicatively coupled to a processor (not shown) that generates the content to be displayed at the eye-wearable display 100. The light engine scans light over a variable area designated as the FOV region 106 of the display system 100. The size of the scanning area corresponds to the size of the FOV region 106, and the position of the scanning area corresponds to such an area of one of the lens elements 108, 110 where the FOV region 106 is visible to the user. Generally, it is desirable for the display to have a wide FOV to accommodate light output coupling across a wide angular range. Herein, the range of different user eye positions at which the display can be seen is referred to as the eyebox of the eye-wearable display 100.

[0030] As previously mentioned, the waveguide is integrated into one or both of the lens elements 108, 110. In some configurations, the waveguide includes a single waveguide substrate, and in other configurations, the waveguide includes multiple waveguide substrates (referred to as a waveguide stack) stacked on top of each other. In some cases, the waveguide includes one or more of the following: an input coupler for coupling light input from the light engine into the waveguide, an exit pupil expander for expanding the coupled input light in one dimension within the waveguide, and an output coupler for coupling the display light output into the eye movement range of the eye-wearable display 100. In some cases, one or more of the input coupler, the exit pupil expander, and the output coupler are implemented as a corresponding set of reflective facets in the waveguide. For example, the output coupler is implemented as multiple sets of reflective facets that receive light from the exit pupil expander and redirect the light out of the waveguide towards the user via the FOV region 106. In some embodiments, each set of reflective facets in the multiple sets of reflective facets includes a first reflective facet that reflects light having a first optical characteristic (e.g., a first wavelength range) in an output coupling direction corresponding to the FOV region 106, and a second reflective facet that reflects light having a second optical characteristic (e.g., a second wavelength range) in the output coupling direction. The first reflective facet in each set of reflective facets overlaps with the first reflective facet in an adjacent set of reflective facets, and the second reflective facet in each set of reflective facets overlaps with the second reflective facet in an adjacent set of reflective facets. This minimizes or eliminates gaps in the light output-coupled via the FOA region 106, thereby improving the optical performance of the eye-wearable display 100.

[0031] Figure 2 FIG. shows a projection system 200 that projects an image onto a user's eye 216 according to various embodiments. The projection system 200 that can be implemented in the Figure 1 eye-wearable display 100 includes one or more of a light engine 202, an optical scanner 220, and / or a waveguide 210. In this example, the optical scanner 220 includes a first scanning mirror 204, a second scanning mirror 206, and an optical relay 208. The waveguide 210 includes one or more input couplers 212 and one or more output couplers 214, where one or more of the output couplers 214 are optically aligned with the user's eye 216. For example, one or more of the output couplers 214 substantially overlap with the Figure 1 FOV region 106 shown in

[0032] The light engine 202 includes one or more light sources configured to generate and output light 218 (e.g., visible light such as red, blue, and green lasers and / or invisible lasers such as infrared lasers). In some embodiments, the light engine 202 is coupled to a controller or driver (not shown) that controls the timing of light emission from the light sources of the light engine 202 (e.g., in accordance with instructions received by the controller or driver from a computer processor coupled thereto) to modulate the light 218 to be perceived as an image when output to the retina of the user's eye 216. For example, during operation of the projection system 200, one or more beams of display light 218 are output by the light sources of the light engine 202 and then directed into the waveguide 210 before being directed to the user's eye 216. The light engine 202 modulates the respective intensities of the light beams such that the combined light reflects a series of pixels of an image, where the specific intensity of each light beam at any given point in time contributes to the corresponding color content and amount of luminance in the pixel represented by the combined light at that time.

[0033] In some embodiments, the optical scanner 220 includes a first scanning mirror 204, a second scanning mirror 206, and an optical relay 208. In some embodiments, one or both of the scanning mirrors 204 and 206 are MEMS mirrors. For example, the scanning mirror 204 and the scanning mirror 206 are MEMS mirrors that are driven by respective actuation voltages to oscillate during active operation of the laser projection system 200, thereby causing the scanning mirrors 204 and 206 to scan the laser light 218. The oscillation of the scanning mirror 204 causes the light 218 output by the optical engine 220 to be scanned through the optical relay 208 and across the surface of the second scanning mirror 206. The second scanning mirror 206 scans the light 218 received from the scanning mirror 204 toward the input coupler 212 of the waveguide 210.

[0034] The waveguide 210 of the projection system 200 includes an input coupler 212 and an output coupler 214. As used herein, the term "waveguide" will be understood to mean a combiner that uses total internal reflection (TIR) or a combination of TIR, a dedicated filter, and / or a reflective surface to convey light from the input coupler to the output coupler. In some display applications, for example, the light represents a collimated image, and the waveguide conveys and reproduces the collimated image to the eye. Generally, the terms "input coupler" and "output coupler" will be understood to refer to any type of optical grating structure, including but not limited to a set of reflective facets, a diffraction grating, a tilted grating, a blazed grating, a holographic plate, a holographic optical element (e.g., an optical element using one or more holographic plates), a volume diffraction grating, a volume holographic plate, a surface relief diffraction grating, and / or a surface relief holographic plate. In some embodiments, the input coupler 212, the exit pupil expander ( Figure 2One or more of (not shown in the figure) and the output coupler 214 are implemented in the waveguide 210 by the multiple sets of reflective facets described herein. In this example, the light 218 received at the input coupler 212 is propagated through the waveguide 210 using TIR to the output coupler 214. Then, the laser 218 is output to the user's eye 216 via the output coupler 214.

[0035] Figure 3 shows Figure 2 A plan view of an example of light propagation within the waveguide 210 of the projection system 200 is shown. As shown, light is received via the input coupler 212, directed as light 320 into the exit pupil expander (EPE) 316, and then directed as light 322 to the output coupler 214 for output from the waveguide 212 towards the user's eye (e.g., the light is reflected by the output coupler 214 in a direction out of the page). In some embodiments, the exit pupil expander 316 expands one or more dimensions of the eye movement range of the eye-wearable display including the laser projection system 200 (e.g., relative to the dimensions of the eye movement range of the eye-wearable display without the exit pupil expander 316). In some embodiments, at least one of the input coupler 212, the exit pupil expander 316, and the output coupler 214 each includes a multiple set of reflective facets. For example, at the input coupler 212, a first multiple set of reflective facets 312 (one is labeled for clarity) receives light emitted from a light engine (such as from Figure 2 in, Figure 3 a light engine 202 not shown in the figure) and reflects the light such that the light 320 is input-coupled into the waveguide 210. A second multiple set of reflective facets 318 (one is labeled for clarity) at the exit pupil expander 316 receives the input-coupled light 320 and reflects the light such that the light is expanded in a second direction 322 towards the output coupler 214. A third multiple set of reflective facets 314 (one is labeled for clarity) at the output coupler 214 reflects the light received from the exit pupil expander 316 such that the light is output-coupled from the waveguide 210, which corresponds to the output-coupling direction out of the page in this illustration. As further described herein, in some embodiments, each reflective facet in a set of reflective facets (e.g., the reflective facet 314 in the output coupler 214) reflects light having a specific optical property such as a specific wavelength range, and each reflective facet in the set of reflective facets overlaps with a reflective facet in an adjacent set of reflective facets that reflects light having the same optical property. This eliminates or reduces gaps in the light reflected from the corresponding optical component (e.g., from the output coupler 214).

[0036] Figure 4FIG. 400 shows a cross-sectional view of a set of conventional reflective facets 420-428 in an exemplary waveguide (not shown for clarity) and associated problems. For example, when implemented as an output coupler in a waveguide, the set of conventional reflective facets 420-428 receives light from an exit pupil expander in a first direction indicated by arrow 401 and redirects the light out of the waveguide to a user in a second direction indicated by arrow 403.

[0037] Generally, substrate 402 is fabricated by a molding process and is made of at least partially transparent plastic or polymer material. The molded substrate 402 includes a plurality of flat surfaces 418 (one is labeled for clarity). The molded substrate 402 also includes a plurality of sub-flat surfaces 430 (one is labeled for clarity). The set of conventional reflective facets 420-428 is formed by applying a reflective coating to the plurality of flat surfaces 418. Ideally, the plurality of flat surfaces 418 of substrate 402 have sharp corners and the sub-flat surfaces are vertical such that there are no gaps between adjacent reflective facets in the set of reflective facets. In practice, a molded plastic substrate such as substrate 402 does not meet this ideal shape and instead includes rounded tops 444 (one is labeled for clarity) and rounded roots 442 (one is labeled for clarity). Additionally, the sub-flat surfaces 430 of a molded plastic substrate such as substrate 402 are not vertical and provide a draft angle 440 (one is labeled for clarity) between the root 442 of one conventional reflective facet 428 and the top 444 of an adjacent conventional reflective facet 426. The combination of the rounded edges (i.e., roots 442 and tops 442) and the draft angle 440 results in gaps between adjacent conventional reflective facets in the set of conventional reflective facets 420-428, which in turn creates gaps in the light reflected by the set of conventional reflective facets 420-428. For example, referring to conventional reflective facets 422 and 424, there is a gap 452 between light 450-1 reflected by conventional facet 424 and light 450-2 reflected by conventional facet 422. These gaps 452 result in discontinuities in the virtual image delivered to the user and thus result in degraded optical performance.

[0038] Figure 5 FIG. shows a cross-sectional view of components of a stack 500 according to some embodiments. In some aspects, a stack such as stack 500 is used to fabricate each set of reflective facets in a waveguide assembly (such as Figure 2 and Figure 3 the output coupler 214 of Figure 2 and Figure 3 the waveguide 210) as described herein) of a plurality of sets of reflective facets in a waveguide component.

[0039] In some embodiments, the stack 500 includes reflective coating layers 502, 504, 506 and carrier film layers 512, 514, 516 and spacer film layer 520. The reflective coating layers 502, 504, 506 (also referred to as reflective coatings) are dichroic coatings, dielectric coatings, metal coatings, holographic coatings, etc. Each of the reflective coatings 502, 504, 506 is configured to reflect light having specific optical properties such as a specific wavelength range (i.e., the color of light) or a specific polarization state. For example, the first reflective coating 502 is a dichroic mirror that reflects blue light. In some embodiments, the first reflective coating 502 also transmits green light and red light. Additionally, the second reflective coating 504 is a second dichroic mirror that reflects green light. In some embodiments, the second reflective coating 504 also transmits blue light and red light. Additionally, the third reflective coating 506 is a third dichroic mirror that reflects red light. In some embodiments, the third reflective coating 506 also transmits blue light and green light. In this way, each of the reflective coatings 502, 504, 506 is tuned or designed to reflect light having specific optical properties (e.g., wavelength range) different from those of the other reflective coatings among the reflective coatings 502, 504, 506 in the stack 500. The thickness of the reflective coatings 502, 504, 506 varies based on the manner in which the reflective coatings 502, 504, 506 are applied to the respective carrier film layers 512, 514, 516 (e.g., via lamination or other coating techniques). For example, in some embodiments, the thickness of the reflective coatings ranges from a few nanometers (e.g., less than 10 nanometers) up to about 10 micrometers.

[0040] Each of the reflective coatings 503, 504, 506 is respectively applied to one of the carrier film layers 512, 514, 516 (also simply referred to as carrier films). In some embodiments, the carrier films 512, 514, 516 are substantially (if not completely) transparent plastic or polymer film substrates. For example, in some cases, the materials for the carrier films 512, 514, 516 are selected such that their refractive indices match the refractive index of the material selected for the waveguide substrate (such as the substrate for Figure 2 and Figure 3 the waveguide 210 in). In some configurations, the carrier film layers 512, 514, 516 have the same thickness, and in other configurations, each of the carrier film layers 512, 514, 516 has a different thickness. The thickness of the carrier films 512, 514, 516 can range from about 50 micrometers to 200 micrometers. In some embodiments, the thickness of the carrier films 512, 514, 516 is designed to keep the separated color films (i.e., the reflective coatings) closer together.

[0041] In addition to the reflective coatings 502, 504, 506 and the carrier films 512, 514, 516, in some embodiments, the stack 500 further includes a spacer film layer 520 (also simply referred to as the spacer film). In some cases, the spacer film 520 is made of the same material as that selected for the carrier films 512, 514, 516. That is, the material of the spacer film 520 is selected such that its refractive index matches the refractive index of the material selected for the waveguide substrate (such as the substrate for the Figure 2 and Figure 3 waveguide 210 therein). In some embodiments, the thickness of the spacer film ranges from 50 microns to 200 microns.

[0042] Although shown in Figure 5 as including three reflective coating layers, in other embodiments, the stack 500 includes another number of reflective coatings (e.g., two or four) spaced apart in the manner described herein. For example, in some embodiments, the stack 500 includes two reflective coatings 502, 504 applied to the respective carrier films 512, 514, rather than the three reflective coatings 502, 504, 506 applied to the respective carrier films 512, 514, 516 as shown in Figure 5 (i.e., the reflective coating 506 and the carrier film 516 are omitted from the stack). Additionally, although described as a dichroic mirror tuned to reflect and transmit light of different colors, in some embodiments, the reflective coatings 502, 504, 506 are holographic plates tuned to reflect and / or transmit light of different colors, or polarization-selective mirrors tuned to reflect and / or transmit light having different polarization states (e.g., p-polarization, s-polarization, etc.).

[0043] In some embodiments, the specific configuration of the stack 500 (e.g., the number of reflective coating layers in the stack 500 and the thicknesses of the different layers) can be tuned depending on the optical component for which it is used in the waveguide. For example, the configuration of the stack 500 depends on whether the stack 500 will be used in an input coupler (such as the input coupler 212 of the Figure 2 and Figure 3 waveguide 210), an exit pupil expander (such as the exit pupil expander 316 of Figure 3 ), or an output coupler (such as the output coupler 214 of the Figure 2 and Figure 3 waveguide 210) to form a reflective facet and is designed and tuned accordingly.

[0044] Figure 6 shows, according to some embodiments, in connection with Figure 5Cross-sectional view of a single-layered stacked stack 600 (i.e., the assembled stacked stack) corresponding to the stacked stack 500. As shown, the single-layered stacked stack 600 includes reflective coatings 502, 504, 516 each configured to reflect light having specific optical properties within a specific wavelength range such as light. Additionally, the reflective coatings 502, 504, 516 are spaced apart from each other in the single-layered stacked stack 600 by carrier films 512, 514, 516. The single-layered stacked stack 600 also includes a spacer film 520, which in this view operates as the substrate of the stacked stack 600.

[0045] In this way, the single-layered stacked stack 600 includes a plurality (three in this example) of reflective coatings that will form a set of reflective facets in the final waveguide structure, as shown and described in the figures that follow.

[0046] Figure 7 A cross-sectional view of the final stacked stack 700 according to some embodiments is shown. The final stacked stack 700 includes a plurality of stacked stacks 600-1, 600-2, 600-3, 600-4 each corresponding to the Figure 6 stacked stack 600. As shown, the final stacked stack 700 may also include a capping spacer film 702. In some aspects, the capping spacer film 702 is made of the same material as the spacer film 520. In some embodiments, the capping spacer film 702 has a thickness in the range from about 400 microns to about 2 millimeters. In some embodiments, the thickness of the capping spacer film 702 may be similar to or the same as the thickness of the spacer film 520.

[0047] The final stacked stack 700 thus includes a plurality of stacked stacks 600-1, 600-2, 600-3, 600-4, and each of the stacked stacks 600-1, 600-2, 600-3, 600-4 includes a plurality of reflective coatings, as Figure 6 shown and described (not labeled in Figure 7 for clarity). In this way, the final stacked stack 700 includes components that form a plurality of sets of reflective facets (e.g., each set of reflective facets corresponds to one of the stacked stacks 600-1, 600-2, 600-3, 600-4), and these components in turn include components that form a plurality of reflective facets (e.g., the plurality of reflective coatings in each of the stacked stacks 600-1, 600-2, 600-3, 600-4 as Figure 5 and Figure 6 shown). Although in Figure 76. Although shown in FIG. 6 as including four lamination stacks 600-1, 600-2, 600-3, 600-4, in other embodiments, the final lamination stack 700 includes another number of lamination stacks 600 (ie, other than four).

[0048] Figure 8 According to some embodiments, Figure 7 802, 804, 806 are each formed along a common cutting angle 810 ranging from 15° to 45°, the range depending on the specific facet angle in the completed waveguide. For example, in some embodiments, the common cutting angle 810 for cutting 802, 804, 806 is approximately 30°. The length of the interval 812 between the cuts is selected based on the final size of the reflective facets and the desired waveguide thickness (only one is labeled for clarity). In some embodiments, the length of the interval 812 ranges from 400 microns to 2 millimeters. In some aspects, the cuts 802, 804, 806 are performed by mechanical techniques (e.g., using a saw blade, etc.), laser cutting techniques, or a combination thereof.

[0049] Figure 9 According to some embodiments, a Figure 8 The optical component segment 900 having multiple reflective facets produced by the cutting as shown. For example, as described in the following figures, the optical component segment 900 is included in an eye-wear display (e.g., such as Figure 1 The waveguide (e.g., such as Figure 2 and Figure 3 in one or more of an input coupler, an exit pupil expander, or an output coupler of a waveguide 210).

[0050] As shown, the optical component segment 900 includes two surfaces 902, 904, which are formed by two cuts (e.g., respectively) made to the final laminated stack 700. Figure 8 That is, the bottom surface 902 is formed by cutting 802, 804. Figure 8 The top surface 904 corresponds to the surface made by the cut 802 of Figure 8corresponds to the surface formed by the cut 804. The optical component segment 900 also includes a plurality of reflecting facet groups 910, 920, 930, 940. Each of the plurality of reflecting facet groups 910, 920, 930, 940 includes a plurality of reflecting facets. For example, the first reflecting facet group 910 includes a first reflecting facet 912, a second reflecting facet 914, and a third reflecting facet 916. Similarly, the second reflecting facet group 920 includes a first reflecting facet 922, a second reflecting facet 924, and a third reflecting facet 926, the third reflecting facet group 930 includes a first reflecting facet 932, a second reflecting facet 934, and a third reflecting facet 936, and the fourth reflecting facet group 940 includes a first reflecting facet 942, a second reflecting facet 944, and a third reflecting facet 946. Each of the corresponding first, second, and third reflecting facets in each of the reflecting facet groups in the reflecting facet groups corresponds to Figure 5 a different respective one of the reflective coatings 502, 504, 506 described in Figures 5 to 7 . That is, referring to the first reflecting facet group 910, the first reflecting facet 912 reflects blue light, the second reflecting facet 914 reflects green light, and the third reflecting facet 916 reflects red light. Each of the first, second, and third reflecting facets in the other reflecting facet groups 920, 930, 940 reflects light in a similar manner. The reflecting facets in each of the reflecting facet groups 910, 920, 930, 940 have a spacing and a facet angle between the other reflecting facets in the reflecting facet group, and the spacing and the facet angle are based on Figures 5 to 7 the thicknesses of the different layers of the stack and the laminated stack described in Figure 8 and the cutting angle described in Figure 8 . In addition, the spacing between the reflecting facet groups (e.g., between the reflecting facet group 910 and the reflecting facet group 920) is similarly based on Figures 5 to 7 the thicknesses of the different layers of the stack and the laminated stack described in Figure 8 and the cutting angle described in Figure 8 to be set.

[0051] In some embodiments, the reflecting facets that reflect light having similar optical properties in adjacent reflecting facet groups overlap each other in the reflection direction indicated by the arrow 950. For example, if the optical component segment 900 is implemented at an output coupler, the reflection direction indicated by the arrow 950 corresponds to the output coupling direction. An example of the overlap portion 952 is shown with respect to the first reflecting facet 912 in the reflecting facet group 910 and the first reflecting facet 922 in the reflecting facet group 920. For example, returning to the previous example, the first reflecting facet 912 in the reflecting facet group 910 and the first reflecting facet 922 in the reflecting facet group 920 correspond to the first reflective coating 502, which is a dichroic mirror that reflects blue light (and transmits green and red light). As Figure 9As shown, the optical component section 900 also includes an overlap (not labeled for clarity) between reflective facets in adjacent reflective facet groups (i.e., reflective facet groups 910, 920, 930, 940) that reflect light having similar optical properties. In this way, the light reflected by the optical component section 900 is uniform and does not include gaps in the light reflected by a conventional reflective facet waveguide, such as Figure 4 the gaps shown and described in

[0052] In some cases, depending on the cutting process used to perform the Figure 8 cuts 802, 804, 806 described in Figure 10 and Figure 11 two examples of surface treatments are shown.

[0053] Figure 10 An example of a first embodiment of a surface treatment 1000 applied to the optical component section 900 of Figure 9 before integration into the final waveguide is shown. The surface treatment 1000 includes applying coatings 1002, 1004 to the surfaces 902, 904 of the optical component section 900, respectively. For example, the coatings 1002, 1004 are applied by spin coating, blade coating, slot coating, or other similar coating techniques. In some embodiments, the coatings 1002, 1004 are anti-reflection coatings or other types of optical coatings having specific optical properties (e.g., made of a material having a specific refractive index selected to match the refractive index of the substrate in the final waveguide). In some cases, the coatings 1002, 1004 improve the surface quality of the optical component section 900 before integration into the final waveguide.

[0054] Figure 11 An example of a second embodiment of a surface treatment 1100 applied to the optical component section 900 of Figure 9 before integration into the final waveguide is shown. The surface treatment 1100 includes laminate layers 1102, 1104 on the surfaces 902, 904 of the optical component section 900, respectively. In some embodiments, the layers 1102, 1104 are anti-reflection laminate layers or other types of optical layers having specific optical properties (e.g., made of a material having a specific refractive index selected to match the refractive index of the substrate in the final waveguide). In some cases, the layers 1102, 1104 improve the surface quality of the optical component section 900 before integration into the final waveguide.

[0055] Figure 12 and Figure 13 show the integration of an optical component section (such as the optical component section 900 of Figure 9 orFigure 10 and Figure 11 An example of integrating an optical component segment corresponding to any one of the surface-treated optical component segments 1000, 1100 into the final waveguide.

[0056] In Figure 12 the optical component segment 1202 is integrated into the final waveguide (such as the waveguide corresponding to the waveguide 210 of Figure 2 and Figure 3 ) by attaching the optical component segment 1202 to the discrete components 1210, 1212 of the waveguide substrate. For example, if the optical component segment 1202 is integrated into the final waveguide as an output coupler (such as the output coupler 214 of Figure 2 and Figure 3 ), then the optical component segment 1202 is assembled with the discrete components 1210, 1212, which include an input coupler and an exit pupil expander (not shown) and the remainder of the waveguide substrate. In some embodiments, the optical component segment 1202 is attached to the discrete components 1210, 1212 of the waveguide substrate via an adhesive material having one or more specific optical properties (e.g., refractive index).

[0057] In Figure 13 the optical component segment 1302 is integrated into the final waveguide (such as the waveguide corresponding to the waveguide 210 of Figure 2 and Figure 3 ) by overcasting or overmolding the optical component segment 1302 into the waveguide substrate 1304. For example, if the optical component segment 1302 is integrated into the final waveguide as an output coupler (such as the output coupler 214 of Figure 2 and Figure 3 ), then the optical component segment 1302 together with the input coupler and the exit pupil expander (not shown) is overmolded into the waveguide substrate 1304. That is, the optical component segment 1302 is overmolded into the waveguide substrate 1304 to form the final waveguide, such as the waveguide 210 shown in Figure 2 and Figure 3 .

[0058] Figure 14 FIG. 1400 shows a flowchart of a method for output-coupling light via an output coupler having overlapping multiple sets of reflective facets (such as the output coupler described with respect to Figures 9 to 13 ).

[0059] At 1402, the method includes output coupling light having a first wavelength range from a first reflective facet of a first set of reflective facets. At 1404, the method includes output coupling light having a second wavelength range from a second reflective facet of the first set of reflective facets. At 1406, the method includes output coupling light having a first wavelength range from a first reflective facet of a second set of reflective facets, the first reflective facet overlapping the first reflective facet of the first set of reflective facets in an output coupling direction. At 1408, the method includes output coupling light having a second wavelength range from a second reflective facet of the second set of reflective facets, the second reflective facet overlapping the second reflective facet of the first set of reflective facets in an output coupling direction.

[0060] In some embodiments, the techniques provided herein eliminate the gaps between reflective facets seen in conventional reflective facet waveguides. Accordingly, the techniques described herein provide a waveguide having reflective facets that deliver a more uniform and higher quality virtual image to a user of an eye-wearable display such as Figure 1 the eye-wearable display shown in

[0061] It should be noted that not all activities or elements described above in the general description are required, that a portion of a specific activity or apparatus may not be required, and that one or more additional activities may be performed or, alternatively, additional elements may be included in addition to those described. Further still, the order in which activities are listed is not necessarily the order in which the activities are performed. Additionally, concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art will understand that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.

[0062] Benefits, other advantages, and solutions to problems have been described above with respect to specific embodiments. However, benefits, advantages, solutions to problems, and any feature that may cause any benefit, advantage, or solution to occur or become more pronounced should not be construed as a critical, required, or essential feature of any or all of the claims. Further, the specific embodiments disclosed above are illustrative only, as the disclosed subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of this disclosure. No limitation is intended as to the details of construction or design shown herein other than as described in the appended claims. Thus, it is evident that the specific embodiments disclosed above may be altered or modified and all such variations are considered within the scope of the disclosed subject matter. Accordingly, the protection sought herein is as set forth in the appended claims.

Claims

1. A waveguide, comprising: a plurality of reflective facet groups, wherein each reflective facet group of the plurality of reflective facet groups includes a first reflective facet for reflecting light having a first optical property and a second reflective facet for reflecting light having a second optical property different from the first optical property, wherein the first reflective facet in the first reflective facet group among the plurality of reflective facet groups overlaps with the first reflective facet in the second group among the plurality of reflective facet groups.

2. The waveguide according to claim 1, wherein, the second reflective facet in the first reflective facet group overlaps with the second reflective facet in the second reflective facet group.

3. The waveguide according to claim 2, wherein, the first optical property is a first wavelength range, and the second optical property is a second wavelength range.

4. The waveguide according to claim 3, wherein, the first wavelength range corresponds to blue light, and the second wavelength range corresponds to red light.

5. The waveguide according to claim 2, wherein, the third reflective facet in the first reflective facet group overlaps with the third reflective facet in the second reflective facet group, and the third reflective facet in the corresponding reflective facet group is for reflecting light having a third optical property different from the first optical property and the second optical property.

6. The waveguide according to claim 5, wherein, the first optical property is a first wavelength range, the second optical property is a second wavelength range, and the third optical property is a third wavelength range.

7. The waveguide according to claim 6, wherein, the first wavelength range corresponds to blue light, the second wavelength range corresponds to green light, and the third wavelength range corresponds to red light.

8. The waveguide according to claim 2, wherein, the first optical property is a first polarization state, and the second optical property is a second polarization state.

9. The waveguide according to claim 1, wherein, the first reflective facet in each reflective facet group transmits light having the second optical property.

10. The waveguide according to claim 1, wherein, the plurality of reflective facet groups are included in an output coupler in the waveguide.

11. The waveguide according to claim 1, wherein, the plurality of reflective facet groups are included in an input coupler or an exit pupil expander in the waveguide.

12. A waveguide, comprising: a first reflective facet group, each reflective facet in the first reflective facet group being configured to reflect light having a specific wavelength range different from other reflective facets in the first reflective facet group; and a second reflective facet group, each reflective facet in the second reflective facet group being configured to reflect light having a specific wavelength range different from other reflective facets in the second reflective facet group, wherein the reflective facets in the first reflective facet group and the second reflective facet group that reflect similar wavelength ranges overlap with each other in the reflection direction.

13. The waveguide according to claim 12, wherein, The first reflective facet group includes a first reflective facet that reflects light in a first wavelength range, a second reflective facet that reflects light in a second wavelength range, and a third reflective facet that reflects light in a third wavelength range.

14. The waveguide according to claim 13, wherein, the first reflective facet transmits light in the second wavelength range and the third wavelength range, and the second reflective facet transmits light in the third wavelength range.

15. The waveguide according to claim 13, wherein, the second reflective facet group includes a first reflective facet that reflects light in the first wavelength range, a second reflective facet that reflects light in the second wavelength range, and a third reflective facet that reflects light in the third wavelength range.

16. The waveguide according to claim 12, wherein, each reflective facet in the corresponding reflective facet group is separated from other reflective facets in the corresponding reflective facet group by a carrier layer.

17. The waveguide according to claim 16, wherein, the first reflective facet group is separated from the second reflective facet group by a spacer layer.

18. The waveguide according to claim 17, wherein, the spacer layer is thicker than the carrier layer.

19. The waveguide according to claim 12, wherein, the first reflective facet group and the second reflective facet group are included in an output coupler in the waveguide.

20. A method for output-coupling light from a waveguide, the method comprises: output-coupling light having a first wavelength range via a first reflective facet in a first reflective facet group and output-coupling light having a second wavelength range via a second reflective facet in the first reflective facet group; and output-coupling light having the first wavelength range via a first reflective facet in a second reflective facet group and output-coupling light having the second wavelength range via a second reflective facet in the second reflective facet group, wherein the first reflective facet in the first reflective facet group overlaps with the first reflective facet in the second reflective facet group in an output-coupling direction, and the second reflective facet in the first reflective facet group overlaps with the second reflective facet in the second reflective facet group in the output-coupling direction.

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