Reflective faceted waveguide with stacked facet layers

Abstract

The waveguide includes a plurality of reflective facet sets, each of which 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, and a first reflective facet in a first of the plurality of reflective facet sets overlaps a first reflective facet in a second of the plurality of reflective facet sets.

Description

[Background technology]

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

[0002] In some cases, one or more of the in-coupler, exit pupil expander, and out-coupler are implemented within the waveguide as a set of reflective facets. Conventional waveguides with reflective facets are often susceptible to degraded optical performance due to discontinuities in the virtual image delivered to the user. Summary of the Invention

[0003] Various embodiments include a waveguide having overlapping sets of reflective facets that reduce or eliminate discontinuities in the light outcoupled by the waveguide.

[0004] In a first embodiment, the waveguide includes a plurality of sets of reflective surfaces, each set of reflective facets including 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, and a first reflective facet in a first set of the plurality of sets of reflective facets overlaps a first reflective facet in a second set of the plurality of sets of reflective facets.

[0005] In some aspects of the first embodiment, a second reflective facet of the first reflective facet set overlaps a second reflective facet of the second reflective facet set. 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, a third reflective facet of the first reflective facet set overlaps a third reflective facet of the second reflective facet set. The third reflective facet in each corresponding reflective facet set 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, a first reflective facet in each set of reflective facets transmits light having the second optical property.

[0008] In some aspects of the first embodiment, the plurality of reflective facet sets are included in an out-coupler within the waveguide, hi some aspects, the plurality of reflective facet sets are additionally or alternatively included in an in-coupler within the waveguide, or in an exit pupil expander.

[0009] In a second embodiment, the waveguide includes a first set of reflective facets and a second set of reflective facets, each reflective facet of the first set configured to reflect light having a specific wavelength range different from other reflective facets in the first set, and each reflective facet of the second set configured to reflect light having a specific wavelength range different from other reflective facets in the second set, and the reflective facets in the first and second sets reflecting similar wavelength ranges overlap each other in the reflection direction.

[0010] In some aspects of the second embodiment, the first set of reflective facets 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 and third wavelength ranges, and the second reflective facet transmits light in the third wavelength range. In some aspects, the second set of reflective facets similarly 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. In some aspects, each reflective facet in a corresponding set of reflective facets is separated from the other reflective facets in the corresponding set by a carrier layer. In some aspects, the first set of reflective facets is separated from the second set of reflective facets by a spacer layer. For example, the spacer layer may be thicker than a carrier layer separating the reflective facets of the corresponding reflective facet sets. In some cases, the first and second reflective facet sets are included in an outcoupler within the waveguide.

[0011] In a third embodiment, a method for outcoupling light from a waveguide includes outcoupling light having a first wavelength range through a first reflective facet in a first set of reflective facets and outcoupling light having a second wavelength range through a second reflective facet in the first set of reflective facets, and outcoupling light having the first wavelength range through the first reflective facet in the second set of reflective facets and outcoupling light having the second wavelength range through the second reflective facet in the second set of reflective facets. In some cases, the first reflective facet in the first set of reflective facets overlaps with the first reflective facet in the second set of reflective facets in the outcoupling direction, and the second reflective facet in the first set of reflective facets overlaps with the second reflective facet in the second set of reflective facets in the outcoupling direction.

[0012] The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings, in which: The use of the same reference symbols in different drawings indicates similar or identical items. [Brief explanation of the drawings]

[0013] [Figure 1] 1 illustrates an exemplary eyewear display, according to some embodiments. [Figure 2] 2 illustrates an example of a projection system having a light filter positioned between a light engine and an in-coupler of a waveguide of an eyewear display, such as that shown in FIG. 1, according to some embodiments. [Figure 3] 3 shows a plan view illustrating an example of light propagation in a waveguide of the projection system of FIG. 2 according to some embodiments. [Figure 4] 1 shows an example of a conventional reflective facet configuration and the problems associated with such a configuration. [Figure 5] 1A-1C show cross-sectional views of components of a stack used to create a set of reflective facets in a waveguide, according to some embodiments. [Figure 6]6A-6C illustrate cross-sectional views of components of the stack, both shown in FIG. 5, according to various embodiments. [Figure 7] 7 illustrates a cross-sectional view of a final laminate stack including multiple laminated stacks as shown in FIG. 6, according to some embodiments. [Figure 8] 8 illustrates a cross-sectional view of cuts made to the final laminate stack of FIG. 7, according to some embodiments. [Figure 9] 9 illustrates a segment of an optical component having multiple reflective facet sets resulting from cuts made as shown in FIG. 8, according to some embodiments. [Figure 10] 10 illustrates an example of a surface treatment performed on a segment of the optical component of FIG. 9, according to some embodiments. [Figure 11] 10 illustrates an example of a surface treatment performed on a segment of the optical component of FIG. 9, according to some embodiments. [Figure 12] 10A-10C illustrate examples of integrating segments of optical components, such as those shown in FIGS. 9-11, into a final waveguide, such as the waveguide shown in FIGS. 2 and 3, according to some embodiments. [Figure 13] 10A-10C illustrate examples of integrating segments of optical components, such as those shown in FIGS. 9-11, into a final waveguide, such as the waveguide shown in FIGS. 2 and 3, according to some embodiments. [Figure 14] 1 shows a flowchart describing a method for outcoupling light through an outcoupler having an overlapping set of reflective facets, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0014] A reflective facet waveguide includes one or more sets of reflective facets to implement one or more of an in-coupler, an out-coupler, or an exit pupil expander. Using an out-coupler as an example, the out-coupler is realized as a set of reflective facets that receive light from the exit pupil expander and reflect the light from within the waveguide to the user. Typically, the set of reflective facets is fabricated 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 on both edges and no gaps between adjacent reflective facets. However, in reality, conventional molded plastic substrates have flat surfaces with rounded edges and draft angles (i.e., non-perpendicular angles) between the flat surfaces due to limitations of the molding process. 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 out-coupled light, which in turn causes discontinuities in the virtual image delivered to the user. For example, if the virtual image is assumed to be a line, gaps in the outcoupled light create "blips" in the line perceived by the user. Described herein are waveguides with overlapping, stacked reflective facets that eliminate discontinuities in the light outcoupled by the waveguide, thereby improving the optical performance of the waveguide and eyewear display.

[0015] For example, in some embodiments, the waveguide includes an in-coupler, an exit pupil expander, and an out-coupler. At least one of these waveguide components, such as the out-coupler, is embodied within the waveguide as a plurality of reflective facet sets. Each of the plurality of reflective facet sets has several reflective facets, and each reflective facet reflects light having a particular optical characteristic in the out-coupling direction. For example, in some embodiments, each reflective facet set has a first reflective facet that reflects blue light in the out-coupling direction, a second reflective facet set that reflects green light in the out-coupling direction, and a third reflective facet that reflects red light in the out-coupling direction. Furthermore, 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. Furthermore, the first, second, and third reflective facets in each set of reflective facets overlap with corresponding first, second, and third reflective facets in adjacent sets of reflective facets. In this manner, the overlapping sets of reflective facets eliminate gaps in light being outcoupled from the waveguide, thereby improving the image quality perceived by a user.

[0016] FIG. 1 illustrates an exemplary eyewear display 100 according to various embodiments. The eyewear display 100 (also referred to as a wearable head-up display (WHUD), head-mounted display (HMD), near-eye display, etc.) has a support structure 102 including an arm 104 that houses a microdisplay projection system configured to project images toward a user's eyes, such that the user perceives the projected images as displayed in a display field of view (FOV) area 106 on one or both of lens elements 108, 110. In the illustrated embodiment, the support structure 102 of the eyewear display 100 is configured to be worn on the user's head and has the general shape and appearance (i.e., "form factor") of an eyeglass frame. The support structure 102 houses or otherwise includes various components for facilitating the projection of such images toward the user's eyes, such as a light engine and waveguides (e.g., shown in FIG. 2 ). In some embodiments, the support structure 102 further includes various sensors, such as one or more front-facing cameras, rear-facing 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. Additionally, in some embodiments, the support structure 102 includes one or more batteries or other portable power sources for powering the electrical components of the eyewear display 100. In some embodiments, some or all of these components of the eyewear display 100 are housed completely or partially within the interior volume of the support structure 102, such as within the arms 104 in the region 112 of the support structure 102. Note that while an exemplary form factor is shown, it is understood that in other embodiments, the eyewear display 100 may have a different shape and appearance than the eyeglass frames shown in FIG. 1 .

[0017] One or both of the lens elements 108, 110 may be used by the eyewear display 100 to provide an augmented reality (AR) or mixed reality (MR) display, in which rendered graphical content may be superimposed on or otherwise provided in conjunction with a view of the real world perceived by a user through the lens elements 108, 110. In some embodiments, one or both of the lens elements 108, 110 function as a light combiner that combines ambient light (also referred to as ambient light) from outside the eyewear display 100 with light emitted from a light engine of the eyewear display 100. For example, the light used to form a perceptible image or series of images may be projected by the light engine of the eyewear display 100 to the user's eye via a series of optical elements, such as a waveguide, one or more scanning mirrors, one or more optical relays, and / or one or more prisms, that are at least partially formed in the corresponding lens element. Thus, one or both of lens elements 108, 110 include at least a portion of a waveguide that transmits display light received by a waveguide in-coupler to a waveguide out-coupler, thereby outputting the display light toward the eye of a user of eyewear display 100. The display light is modulated and projected to the user's eye such that the user perceives the display light as an image within FOV region 106. Furthermore, in some embodiments, each of lens elements 108, 110 is sufficiently transparent to allow the user to see through the lens element, thereby providing a view of the user's real-world environment, such that the image appears superimposed on at least a portion of the real-world environment.

[0018] In some embodiments, the light engine is a matrix-based projector, a scanning laser projector, or any combination of 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, the light engine includes, for example, multiple laser diodes (e.g., red, green, and / or blue laser diodes) and at least one scan mirror (e.g., two one-dimensional scan mirrors that are microelectromechanical systems (MEMS)-based or piezoelectric). 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 that, when executed by the controller, cause the controller to control the operation of the projector. In some embodiments, the controller is communicatively coupled to a processor (not shown) that controls the scan area size and scan area position of the light engine and generates the content displayed on the eyewear display 100. The light engine scans light over a variable area of ​​the display system 100, designated as the FOV area 106. The scan region size corresponds to the size of the FOV region 106, and the scan region position corresponds to the 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 outcoupling over a wide range of angles. Herein, the range of different user eye positions from which the display can be viewed is referred to as the eyebox of the eyewear display 100.

[0019] 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, while in other configurations, the waveguide includes multiple waveguide substrates stacked on top of each other (called a waveguide stack). The waveguide, in some cases, includes one or more of: an in-coupler for incoupling light from a light engine into the waveguide; an exit pupil expander for expanding the incoupled light in one dimension into the waveguide; and an out-coupler for outcoupling display light to the eyebox of the eyewear display 100. In some cases, one or more of the in-coupler, exit pupil expander, and out-coupler are implemented within the waveguide as corresponding sets of reflective facets. For example, the out-coupler is embodied as a set of multiple reflective facets that receive light from the exit pupil expander and redirect the light from within the waveguide to the user through the FOV region 106. In some embodiments, each reflective facet set of the plurality of reflective facet sets includes a first reflective facet that reflects light having a first optical characteristic (e.g., a first wavelength range) in an outcoupling direction corresponding to FOV region 106, and a second reflective facet that reflects light having a second optical characteristic (e.g., a second wavelength range) in the outcoupling direction. The first reflective facet in each reflective facet set overlaps with the first reflective facet in an adjacent reflective facet set(s), and the second reflection in each reflective facet set overlaps with the second reflective facet in the adjacent reflective facet set(s). This minimizes or eliminates gaps in the light outcoupling through FOV region 106, thereby improving the optical performance of eyewear display 100.

[0020] FIG. 2 shows a diagram of a projection system 200 that projects an image to a user's eye 216, according to various embodiments. The projection system 200, which may be implemented in the eyewear display 100 of FIG. 1, 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 scan mirror 204, a second scan mirror 206, and an optical relay 208. The waveguide 210 includes one or more in-couplers 212 and one or more out-couplers 214, where the one or more out-couplers 214 are optically aligned with the user's eye 216. For example, the one or more out-couplers 214 substantially overlap with the FOV region 106 shown in FIG. 1.

[0021] 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 light, and / or non-visible laser light such as infrared laser light). In some embodiments, light engine 202 is coupled to a controller or driver (not shown), which controls the timing of light emission from the light sources of light engine 202 (e.g., according to instructions received by the controller or driver from a computer processor coupled thereto) to modulate light 218 so that it is perceived as an image upon output to the retina of a user's eye 216. For example, during operation of projection system 200, one or more beams of display light 218 are output by the light source(s) of light engine 202 and then directed into waveguide 210 before being directed to the user's eye 216. The light engine 202 modulates the intensity of each of the light beams so that the combined light reflects off a series of pixels of the image, and the particular intensity of each light beam at any given time contributes to the corresponding color content and amount of brightness of the pixel represented by the combined light at that time.

[0022] In some embodiments, the optical scanner 220 includes a first scan mirror 204, a second scan mirror 206, and an optical relay 208. In some embodiments, one or both of the scan mirrors 204 and 206 are MEMS mirrors. For example, the scan mirrors 204 and 206 are MEMS mirrors that are driven by respective actuation voltages to oscillate during active operation of the laser projection system 200, causing the scan mirrors 204 and 206 to scan the laser light 218. The oscillation of the scan mirror 204 causes the light 218 output by the optical engine 202 to be scanned across the surface of the second scan mirror 206 through the optical relay 208. The second scan mirror 206 scans the light 218 received from the scan mirror 204 toward the in-coupler 212 of the waveguide 210.

[0023] The waveguide 210 of the projection system 200 includes an in-coupler 212 and an out-coupler 214. The term “waveguide,” as used herein, is understood to mean a combiner that transmits light from an in-coupler to an out-coupler using total internal reflection (TIR) ​​or a combination of TIR, special filters, and / or reflective surfaces. In a display application, for example, the light represents a collimated image, and the waveguide transmits and replicates the collimated image to the eye. In general, the terms “in-coupler” and “out-coupler” are 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 diffraction grating, a hologram, a holographic optical element (e.g., an optical element that uses one or more holograms), a volume diffraction grating, a volume hologram, a surface-relief diffraction grating, and / or a surface-relief hologram. In some embodiments, one or more of in-coupler 212, exit pupil expander (not shown in FIG. 2), and out-coupler 214 are implemented within waveguide 210 with multiple reflective facet sets as described herein. In this example, light 218 received at in-coupler 212 is propagated through waveguide 210 to out-coupler 214 using TIR. Laser light 218 is then output through out-coupler 214 to the user's eye 216.

[0024] 3 illustrates a plan view of an example of light propagation within waveguide 210 of projection system 200 of FIG. 2. As illustrated, light is received through in-coupler 212, directed into exit pupil expander (EPE) 316 as light 320, and then sent to out-coupler 214 as light 322 for output from waveguide 212 toward a user's eye (e.g., the light is reflected off the page by out-coupler 214). In some embodiments, exit pupil expander 316 expands one or more dimensions of the eyebox of the eyewear display that includes laser projection system 200 (e.g., relative to the dimensions the eyebox of the eyewear display would have without exit pupil expander 316). In some embodiments, at least one of in-coupler 212, exit pupil expander 316, and out-coupler 214 each include multiple sets of reflective facets. For example, at in-coupler 212, a first plurality of reflective facets set 312 (labeled for clarity) receives light emitted from a light engine (not shown in FIG. 3 , such as from light engine 202 of FIG. 2 ) and reflects the light so that light 320 is incoupled into waveguide 210. A second plurality of reflective facets set 318 (labeled for clarity) at exit pupil expander 316 receives the incoupled light 320 and reflects the light so that the light is expanded in a second direction 322 toward out-coupler 214. A third plurality of reflective facets set 314 (labeled for clarity) at out-coupler 214 reflects the received light from exit pupil expander 316 so that the light is outcoupled from waveguide 210, which in this illustration corresponds to an out-coupling direction out of the page. As described further herein, in some embodiments, each reflective facet within a reflective facet set (e.g., reflective facet set 314 within outcoupler 214) reflects light having particular optical properties, such as a particular wavelength range, and each reflective facet within a reflective facet set overlaps with a reflective facet in an adjacent reflective facet set that reflects light having the same optical properties.This eliminates or reduces gaps in the light reflected from each optical component (eg, from outcoupler 214).

[0025] 4 shows a cross-sectional view 400 illustrating a set of conventional reflective facets 420-428 within a waveguide (not shown for clarity) and the associated problems. For example, when implemented within the waveguide as an outcoupler, the set of conventional reflective facets 420-428 receives light coming from an exit pupil expander in a first direction indicated by arrow 401 and redirects the light from within the waveguide to a user in a second direction indicated by arrow 403.

[0026] Typically, substrate 402 is fabricated by a molding process and is made from a plastic or polymer material that is at least partially transparent. Molded substrate 402 includes a plurality of planar surfaces 418 (labeled for clarity). Molded substrate 402 also includes a plurality of secondary planar surfaces 430 (labeled for clarity). A set of conventional reflective facets 420-428 is formed by applying a reflective coating to the plurality of planar surfaces 418. Ideally, the plurality of planar surfaces 418 of substrate 402 have sharp corners and the secondary planar surfaces are vertical, so that there are no gaps between adjacent reflective facets. In practice, molded plastic substrates such as substrate 402 do not meet this ideal shape and instead include a rounded tip 444 (labeled for clarity) and a rounded base 442 (labeled for clarity). Additionally, the secondary plane 430 of a molded plastic substrate, such as substrate 402, is not vertical, but rather provides a draft 440 (labeled draft for clarity) between the base 442 of one conventional reflective facet 428 and the tip 444 of an adjacent conventional reflective facet 426. The rounded edges (i.e., base 442 and tip 442) combined with the draft 440 create gaps between adjacent reflective facets of conventional reflective facets 420-428, which in turn create gaps in the light reflected by the set of conventional reflective facets 420-428. For example, with reference 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 create discontinuities in the virtual image delivered to the user, thus degrading optical performance.

[0027] 5 illustrates 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 create each reflective facet set of multiple reflective facet sets in a waveguide component (such as outcoupler 214 in FIGS. 2 and 3 ) of a waveguide described herein (such as waveguide 210 in FIGS. 2 and 3 ).

[0028] In some embodiments, the stack 500 includes reflective coating layers 502, 504, and 506, carrier film layers 512, 514, and 516, and a spacer film layer 520. The reflective coating layers 502, 504, and 506 (also referred to as reflective coatings) are dichroic coatings, dielectric coatings, metallic coatings, holographic coatings, etc. Each of the reflective coatings 502, 504, and 506 is configured to reflect light having specific optical properties, such as a specific wavelength range (i.e., 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 and red light. Furthermore, 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 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 and green light. Thus, each reflective coating of the reflective coatings 502, 504, 506 is tailored or designed to reflect light having specific optical properties (e.g., wavelength ranges) that are different from the other reflective coatings 502, 504, 506 in the stack 500. The thicknesses of the reflective coatings 502, 504, 506 vary based on how the reflective coatings 502, 504, 506 are applied to their respective carrier film layers 512, 514, 516 (e.g., via lamination or other coating techniques). For example, in some embodiments, the thicknesses of the reflective coatings range from a few nanometers (e.g., less than 10 nanometers) up to about 10 microns.

[0029] Each of the reflective coatings 503, 504, and 506 is applied to one of the carrier film layers 512, 514, and 516 (also referred to simply as carrier films). In some embodiments, the carrier films 512, 514, and 516 are plastic or polymer film substrates that are mostly, if not completely, transparent. For example, in some cases, the material of the carrier films 512, 514, and 516 is selected so that its refractive index matches the refractive index of the material selected for the waveguide substrate, such as the substrate for the waveguide 210 in FIGS. 2 and 3. In some configurations, the thicknesses of the carrier film layers 512, 514, and 516 are the same, while in other configurations, the thicknesses of each of the carrier film layers 512, 514, and 516 are different. The thickness of the carrier films 512, 514, and 516 may range from approximately 50 microns to 200 microns. In some embodiments, the thickness of the carrier films 512, 514, 516 is designed to keep the separate color films (ie, reflective coatings) closer together.

[0030] In addition to the reflective coatings 502, 504, 506 and carrier films 512, 514, 516, the stack 500, in some embodiments, includes a spacer film layer 520 (also simply referred to as a spacer film). In some cases, the spacer film 520 is made from the material selected for the carrier films 512, 514, 516. That is, the material of the spacer film 520 is selected so that its refractive index matches the refractive index of the material selected for the waveguide substrate, such as the substrate for the waveguide 210 in FIGS. 2 and 3. In some embodiments, the thickness of the spacer film is in the range of 50 microns to 200 microns.

[0031] 5 as including three reflective coating layers, in other embodiments, stack 500 includes other numbers of reflective coatings (e.g., two or four) spaced apart in a manner described herein. For example, in some embodiments, stack 500 includes two reflective coatings 502, 504 applied to respective carrier films 512, 514 (i.e., reflective coating 506 and carrier film 516 are omitted from the stack) instead of the three reflective coatings 502, 504, 506 applied to respective carrier films 512, 514, 516 shown in FIG. 5. Furthermore, although described as being dichroic mirrors tuned to reflect and transmit light of different colors, in some embodiments, reflective coatings 502, 504, 506 are holograms 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-polarized, s-polarized, etc.).

[0032] In some embodiments, the specific configuration of stack 500 (e.g., the number of reflective coating layers and the thicknesses of the different layers in stack 500) can be tailored depending on the optical components used in the waveguide. For example, the configuration of stack 500 is designed and tailored depending on whether stack 500 forms a set of reflective facets in an in-coupler (such as in-coupler 212 of waveguide 210 in FIGS. 2 and 3), a set of reflective facets in an exit pupil expander (such as exit pupil expander 316 in FIG. 3), or a set of reflective facets in an out-coupler (such as out-coupler 214 of waveguide 210 in FIGS. 2 and 3).

[0033] 6 illustrates a cross-sectional view of a single laminate stack 600 (i.e., an assembled stack) corresponding to stack 500 of FIG. 5 , according to some embodiments. As shown, single laminate stack 600 includes reflective coatings 502, 504, 516, each configured to reflect light having specific optical properties, such as a specific wavelength range of light. Additionally, reflective coatings 502, 504, 516 are spaced apart from one another within single laminate stack 600 by carrier films 512, 514, 516. Single laminate stack 600 also includes a spacer film 520, which in this illustration serves as a base for laminate stack 600.

[0034] Thus, the single layer stack 600 contains multiple (in this example, three) reflective coatings that form the set of reflective facets in the final waveguide structure as shown and described in subsequent figures.

[0035] FIG. 7 illustrates a cross-sectional view of a final laminate stack 700, according to some embodiments. The final laminate stack 700 includes multiple laminate stacks 600-1, 600-2, 600-3, and 600-4, each corresponding to the laminate stack 600 of FIG. 6. As shown, the final laminate stack 700 may also include a capping spacer film 702. In some aspects, the capping spacer film 702 is made from the same material as the spacer film 520. In some embodiments, the capping spacer film 702 has a thickness ranging 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.

[0036] Thus, the final stack 700 includes multiple stacks 600-1, 600-2, 600-3, 600-4, each including multiple reflective coatings as shown and described in Figure 6 (for clarity, not labeled in Figure 7). In this manner, the final stack 700 includes components forming multiple reflective facet sets (e.g., each reflective facet set of multiple reflective facet sets corresponding to one of the stacks 600-1, 600-2, 600-3, 600-4), which in turn include components forming multiple reflective facets (e.g., multiple reflective coatings of each stack of the stacks 600-1, 600-2, 600-3, 600-4 as described in Figures 5 and 6). Although shown in FIG. 7 as including four lamination stacks 600-1, 600-2, 600-3, 600-4, in other embodiments, the final lamination stack 700 includes other numbers of lamination stacks 600 (ie, other than four).

[0037] FIG. 8 illustrates a cross-sectional view of cuts 802, 804, and 806 made in the final laminate stack 700 of FIG. 7 , according to some embodiments. The cuts 802, 804, and 806 are each made along a common cutting angle 810 ranging from 15° to 45°, depending on the particular facet angle in the finished waveguide. For example, in some embodiments, the common cutting angle 810 for the cuts 802, 804, and 806 is approximately 30°. The length of the spacing 812 between the cuts (only one is labeled for clarity) is selected based on the final dimensions of the reflective facets and the desired waveguide thickness. In some embodiments, the length of the spacing 812 ranges from 400 microns to 2 millimeters. In some aspects, the cuts 802, 804, and 806 are made by mechanical techniques (e.g., using a saw blade), laser cutting techniques, or a combination thereof.

[0038] Figure 9 shows a segment of an optical component 900 having multiple reflective facet sets resulting from cuts made as shown in Figure 8, according to some embodiments. For example, as described in later figures, the segment of optical component 900 may be included in one or more of an in-coupler, an exit pupil expander, or an out-coupler of a waveguide (such as, for example, waveguide 210 in Figures 2 and 3) in an eyewear display (such as, for example, eyewear display 100 in Figure 1).

[0039] As shown, optical component segment 900 includes two surfaces 902, 904 resulting from two cuts (e.g., cuts 802, 804, respectively, in FIG. 8 ) made in final laminate stack 700. That is, bottom surface 902 corresponds to the surface created by cut 802 in FIG. 8 , and top surface 904 corresponds to the surface created by cut 804 in FIG. 8 . Optical component segment 900 also includes multiple reflective facet sets 910, 920, 930, 940. Each set of multiple reflective facet sets 910, 920, 930, 940 includes multiple reflective facets. For example, first reflective facet 910 includes first reflective facet 912, second reflective facet 914, and third reflective facet 916. Similarly, the second reflective facet set 920 includes a first reflective facet 922, a second reflective facet 924, and a third reflective facet 926, the third reflective facet set 930 includes a first reflective facet 932, a second reflective facet 934, and a third reflective facet 936, and the fourth reflective facet set 940 includes a first reflective facet 942, a second reflective facet 944, and a third reflective facet 946. Each reflective facet of the respective first, second, and third reflective facets in each of the reflective facet sets corresponds to a different respective reflective coating from the reflective coatings 502, 504, 506 described in FIG. That is, with reference to the first reflective facet set 910, the first reflective facet 912 reflects blue light, the second reflective facet 914 reflects green light, and the third reflective facet 916 reflects red light. Each reflective facet of the first, second, and third reflective facets in the other reflective facet sets 920, 930, 940 reflects light in a similar manner. The reflective facets in each reflective facet set 910, 920, 930, 940 have facet angles based on the spacing between other reflective facets in the reflective facet set, as well as the thicknesses of the different layers of the stacks and laminate stacks described in Figures 5-7 and the cut angles described in Figure 8.Furthermore, the spacing between reflective facet sets (e.g., between reflective facet set 910 and reflective facet set 920) is similarly set based on the thicknesses of the different layers of the stack and laminate stack described in Figures 5-7, and the cutting angles described in Figure 8.

[0040] In some embodiments, reflective facets that reflect light with similar optical properties in adjacent reflective facet sets overlap each other in the reflection direction indicated by arrow 950. For example, if segment of optical component 900 is implemented in an outcoupler, the reflection direction indicated by arrow 950 corresponds to the outcoupling direction. An example of overlap 952 is shown for the first reflective facet 912 in reflective facet set 910 and the first reflective facet 922 in reflective facet set 920. For example, referring back to the example above, the first reflective facet 912 in reflective facet set 910 and the first reflective facet 922 in reflective facet set 920 correspond to the first reflective coating 502, which is a dichroic mirror that reflects blue light (and transmits green and red light). 9, optical component segment 900 also includes overlaps (not labeled for clarity) between reflective facets in adjacent reflective facet sets (i.e., reflective facet sets 910, 920, 930, 940) that reflect light with similar optical properties. In this manner, the light reflected by optical component segment 900 is uniform and does not include gaps in the light reflected by a conventional reflective facet waveguide, such as the gaps shown and described in FIG.

[0041] In some cases, depending on the cutting process used to make the cuts 802, 804, 806 described in Figure 8, the surfaces 902, 904 of the optical component segment 900 may require surface treatment before integrating the optical component segment 900 into a final waveguide. Two examples of surface treatments are shown in Figures 10 and 11.

[0042] FIG. 10 illustrates an example of a first embodiment of a surface treatment 1000 applied to the optical component segment 900 of FIG. 9 prior to integration into the final waveguide. The surface treatment 1000 includes applying coatings 1002, 1004 onto each of the surfaces 902, 904 of the optical component segment 900. 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-reflective coatings or other types of optical coatings with specific optical properties (e.g., made from materials with specific refractive indices 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 segment 900 prior to integration into the final waveguide.

[0043] 11 shows an example of a second embodiment of a surface treatment 1100 applied to the optical component segment 900 of FIG. 9 prior to integration into the final waveguide. The surface treatment 1100 includes laminating layers 1102, 1104 onto each of the surfaces 902, 904 of the optical component segment 900. In some embodiments, the layers 1102, 1104 are anti-reflective lamination layers or other types of optical layers with specific optical properties (e.g., made from materials with specific refractive indices selected to match the refractive indices of the substrates in the final waveguide). In some cases, the layers 1102, 1104 improve the surface quality of the optical component segment 900 prior to integration into the final waveguide.

[0044] 12 and 13 show examples of integrating optical component segments (such as optical component segment 900 of FIG. 9 or an optical component segment corresponding to any one of the surface-treated optical component segments 1000, 1100 of FIGS. 10 and 11) into a final waveguide.

[0045] 12, optical component segment 1202 is integrated into a final waveguide (such as a waveguide corresponding to waveguide 210 in FIGS. 2 and 3) by attaching optical component segment 1202 to individual components 1210, 1212 of a waveguide substrate. For example, if optical component segment 1202 is integrated into a final waveguide as an out-coupler (such as out-coupler 214 in FIGS. 2 and 3), optical component segment 1202 is assembled with individual components 1210, 1212, including an in-coupler, an exit pupil expander (not shown), and the remainder of the waveguide substrate. In some embodiments, optical component segment 1202 is attached to individual components 1210, 1212 of the waveguide substrate by an adhesive material having one or more particular optical properties (e.g., refractive index).

[0046] 13, optical component segments 1302 are integrated into a final waveguide (such as a waveguide corresponding to waveguide 210 in FIGS. 2 and 3) by overcasting or overmolding optical component segments 1302 into a waveguide substrate 1304. For example, if optical component segments 1302 are integrated into a final waveguide as an outcoupler (such as outcoupler 214 in FIGS. 2 and 3), optical component segments 1302 are overcast into waveguide substrate 1304 along with an incoupler and exit pupil expander (not shown). That is, optical component segments 1302 are overcast into waveguide substrate 1304 to form a final waveguide, such as waveguide 210 shown in FIGS. 2 and 3.

[0047] FIG. 14 illustrates a method flowchart 1400 for outcoupling light through an outcoupler having an overlapping set of reflective facets, such as those described with respect to FIGS. 9-13, according to some embodiments.

[0048] At 1402, the method includes outcoupling light having a first wavelength range from a first reflective facet in the first set of reflective facets. At 1404, the method includes outcoupling light having a second wavelength range from a second reflective facet in the first set of reflective facets. At 1406, the method includes outcoupling light having the first wavelength range from a first reflective facet in the second set of reflective facets that overlaps the first reflective facet in the first set of reflective facets in the outcoupling direction. At 1408, the method includes outcoupling light having the second wavelength range from a second reflective facet in the second set of reflective facets that overlaps the second reflective facet in the first set of reflective facets in the outcoupling direction.

[0049] In some embodiments, the techniques provided herein eliminate the gaps between reflective facets found in conventional reflective facet waveguides. Thus, the techniques described herein provide a waveguide with reflective facets that delivers a more uniform and higher quality virtual image to a user of an eyewear display such as that shown in FIG.

[0050] In addition to the above, it should be noted that not all activities or elements described above in the general description are required, and that some of the specific activities or devices may not be required, or that one or more additional activities may be performed, or that one or more additional elements may be included. Furthermore, the order in which the activities are listed is not necessarily the order in which they are performed. Also, the concepts have been described with reference to specific embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of the present disclosure, as set forth in the claims below. Accordingly, the specification and drawings should be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be within the scope of the present disclosure.

[0051] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, and solutions to problems, as well as any feature or features that may cause or make more pronounced any benefit, advantage, or solution, should not be construed as critical, necessary, or essential features of any or all claims. Moreover, the specific embodiments disclosed above are exemplary only, as the disclosed inventive subject matter may be modified and practiced in different but equivalent manners that will be apparent to those skilled in the art having the benefit of the teachings herein. No limitations are intended to the details of construction or design herein shown, other than as set forth in the claims below. It is therefore apparent that the particular embodiments disclosed above may be altered or modified, and that all such variations are considered within the scope of the disclosed inventive subject matter. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

1. A waveguide, a plurality of reflective facet sets, each reflective facet set of the plurality of reflective facet sets including 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 set of the plurality of sets of reflective facets overlaps a first reflective facet in a second set of the plurality of sets of reflective facets; Waveguide.

2. 2. The waveguide of claim 1, wherein a second reflective facet of the first set of reflective facets overlaps a second reflective facet of the second set of reflective facets.

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

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

5. 3. The waveguide of claim 2, wherein a third reflective facet of the first set of reflective facets overlaps a third reflective facet of the second set of reflective facets, and the third reflective facet in a corresponding set of reflective facets reflects light having a third optical property different from the first optical property and the second optical property.

6. 6. The waveguide of 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. 7. The waveguide of 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. 3. The waveguide of 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 of claim 1 , wherein the first reflective facet in each set of reflective facets transmits light having the second optical property.

10. The waveguide of claim 1 , wherein the plurality of sets of reflective facets are included in an outcoupler within the waveguide.

11. The waveguide of claim 1 , wherein the plurality of sets of reflective facets are included in an in-coupler or exit pupil expander within the waveguide.

12. A waveguide, a first set of reflective facets, each reflective facet of the first set of reflective facets configured to reflect light having a particular wavelength range different from other reflective facets in the first set of reflective facets, the waveguide further comprising: a second set of reflective facets, each reflective facet of the second set of reflective facets configured to reflect light having a particular wavelength range different from other reflective facets in the second set of reflective facets; reflective facets in the first set of reflective facets and the second set of reflective facets that reflect similar wavelength ranges overlap each other in a reflection direction; Waveguide.

13. 13. The waveguide of claim 12, wherein the first set of reflective facets 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. 14. The waveguide of 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. 14. The waveguide of claim 13, wherein the second set of reflective facets 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. 13. The waveguide of claim 12, wherein each reflective facet in a corresponding set of reflective facets is separated from other reflective facets in the corresponding set of reflective facets by a carrier layer.

17. 17. The waveguide of claim 16, wherein the first set of reflective facets is separated from the second set of reflective facets by a spacer layer.

18. 20. The waveguide of claim 17, wherein the spacer layer is thicker than the carrier layer.

19. The waveguide of claim 12 , wherein the first set of reflective facets and the second set of reflective facets are included in an outcoupler within the waveguide.

20. 1. A method for outcoupling light from a waveguide, the method comprising: outcoupling light having a first wavelength range through a first reflective facet in a first set of reflective facets and outcoupling light having a second wavelength range through a second reflective facet in the first set of reflective facets; outcoupling light having the first wavelength range through a first reflective facet in a second set of reflective facets and outcoupling light having the second wavelength range through a second reflective facet in the second set of reflective facets; Including, the first reflecting facet in the first reflecting facet set overlaps with the first reflecting facet in the second reflecting facet set in an outcoupling direction, and the second reflecting facet in the first reflecting facet set overlaps with the second reflecting facet in the second reflecting facet set in the outcoupling direction; method.

Images