Optical device venting gap for edge sealants and lamination dams

Abstract

Embodiments of the present disclosure relate to an optical device, such as an eyepiece, that includes multiple waveguide layers. The optical device can include an edge sealant for reducing light pollution, a lamination dam that limits wicking of the edge sealant between layers of the optical device, and a vent gap in the sealant and dam that allows air flow between the exterior and interior of the eyepiece. The gap allows for venting from the interior of the eyepiece that has unreacted polymer and / or accumulated moisture to prevent the accumulation of defects caused by chemical reactions of the expelled chemicals with the surface (e.g., ionic, acidic, etc.) of the eyepiece layers. The gap also prevents pressure differentials that can physically deform the eyepiece over time.

Description

[0001] This application is a divisional application of patent application filed on July 22, 2019, with application number 201980049076.4 and entitled "Ventilation gap for optical device for edge sealant and laminated dam".

[0002] Cross-reference of related applications

[0003] This application claims the benefit of U.S. Patent Application No. 62 / 702,215, filed July 23, 2018, entitled "OPTICAL DEVICE VENTING GAPS FOR EDGE SEALANT AND LAMINATION DAM", and U.S. Patent Application No. 62 / 702,020, also filed July 23, 2018, entitled "OPTICAL DEVICE VENTING GAPS FOR EDGE SEALANT AND LAMINATION DAM". Background Technology

[0004] In optical devices, light can be directed and / or manipulated to achieve a desired effect. For example, in optical devices such as eyepieces used in virtual reality interfaces, visible light can be directed and / or manipulated to provide image data perceived by the user. Various types of optical devices can be tested during and / or after manufacturing to ensure that the device is manufactured and / or operates according to desired specifications. For example, in some types of optical devices, reducing or eliminating light leakage from outside the device may be advantageous. Summary of the Invention

[0005] Embodiments of this disclosure generally relate to optical devices having one or more venting gaps. More specifically, embodiments relate to an optical device, such as an eyepiece comprising multiple optical layers, the optical device including an edge sealant along at least a portion of the periphery of the optical device, a laminated dam restricting wicking of the edge sealant, and one or more venting gaps located in the laminated dam and the edge sealant allowing airflow between the interior and exterior of the optical device. When the optical device is subjected to thermal and humidity conditions (e.g., at approximately 80-100% relative humidity and approximately 45-65 degrees Celsius), the airflow provided by the vents also allows unreacted polymer residues and moisture to escape from the areas between the layers of the optical device.

[0006] Generally, the innovative aspects of the subject matter described in this specification may be included in one or more embodiments of an optical device comprising: a plurality of optical layers; an edge sealant disposed across the plurality of optical layers along an edge of the optical device, wherein one or more sealant gaps are present in the edge sealant; and a lamination dam disposed between each pair of adjacent layers of the plurality of optical layers to prevent wicking of the edge sealant between the optical layers and at a distance from the edge of the optical device, wherein one or more dam gaps are present in the lamination dam at one or more locations along the edge, each of the one or more locations corresponding to the location of a corresponding sealant gap to allow airflow between the interior and exterior of the optical device through the one or more sealant gaps and the one or more dam gaps. The innovative aspects of the subject matter described in this specification may be included in one or more embodiments of an eyepiece comprising an embodiment of the optical device.

[0007] One or more embodiments may optionally include one or more of the following features.

[0008] In some embodiments, one or more sealant gaps are located outside a critical area at the edge of the optical device.

[0009] In some embodiments, one or more of the sealant gaps have a length along the edge of the optical device that exceeds the length of the corresponding dam gap.

[0010] In some embodiments, one or more of the surfaces of the edge sealant, the laminated dam, and one of the optical layers comprise or are at least partially composed of a hydrophobic material.

[0011] In some embodiments, along the edge of the optical device, at least one of one or more sealant gaps at least partially overlaps with a corresponding one of one or more dam gaps.

[0012] In some embodiments, at least one of one or more sealant gaps is concentric with a corresponding one of one or more dam gaps.

[0013] In some embodiments, the edge sealant includes at least two sealant gaps, and the laminated dam includes at least two dam gaps.

[0014] In some embodiments, the plurality of optical layers includes at least three optical layers. The at least three optical layers include a layer for guiding red light, a layer for guiding green light, and a layer for guiding blue light.

[0015] In some embodiments, the edge sealant absorbs ultraviolet radiation.

[0016] In some embodiments, at least one of the plurality of optical layers includes an orthogonal pupil expander region.

[0017] In some embodiments, at least one of the plurality of optical layers includes an exit pupil expander region.

[0018] In some embodiments, at least one of the plurality of optical layers includes a grating coupling region.

[0019] In some embodiments, one or more sealant gaps and one or more edge gaps allow airflow between the interior and exterior of the optical device.

[0020] In some embodiments, the edge sealant prevents light leakage in the lateral direction from the inside to the outside of the optical device through the edge of the optical device.

[0021] In some embodiments, the edge sealant prevents light from being reflected into the interior of the eyepiece.

[0022] In some embodiments, the thickness of the edge sealant is in the range of about 430 micrometers to about 500 micrometers.

[0023] In some embodiments, the thickness of the edge sealant between the edge of the optical device and the laminated dam is approximately 350 micrometers.

[0024] In some embodiments, the width of the laminated dam is approximately 500 micrometers.

[0025] In some respects, the eyepiece includes

[0026] It should be understood that aspects and features according to this disclosure may include any combination of aspects and features described herein. That is, aspects and features according to this disclosure are not limited to the combinations of aspects and features specifically described herein, but also include any combination of aspects and features provided.

[0027] Details of one or more embodiments of the present disclosure are set forth in the accompanying drawings and the following description. Other features and advantages of the present disclosure will be apparent from the description, the drawings, and the claims. Attached Figure Description

[0028] Figure 1 A schematic diagram of an example eyepiece according to an embodiment of the present disclosure is depicted.

[0029] Figure 2 A schematic diagram depicting a portion of an example eyepiece according to an embodiment of the present disclosure is shown.

[0030] Figure 3 A cross-sectional schematic diagram of an example optical device that can be inspected using an inspection device according to an embodiment of the present disclosure is depicted.

[0031] Figure 4An example dam arrangement in an eyepiece according to an embodiment of the present disclosure is depicted.

[0032] Figure 5 A schematic diagram depicts an example deformation of the eyepiece layer, such as in the absence of a vent.

[0033] Figure 6A and 6B The images shown are scanning electron microscope (SEM) images of eyepiece distortion with and without a vent, according to embodiments of the present disclosure. Detailed Implementation

[0034] Embodiments of this disclosure relate to optical devices, such as eyepieces, which include an edge sealant for reducing light pollution, a laminated dam that restricts wicking of the edge sealant between layers of the optical device, and a gap located in the sealant and the dam that allows venting from the interior of the eyepiece and prevents pressure differentials. The gap allows air to flow between the interior and exterior of the eyepiece and prevents defects and / or deformations that may be caused by additional chemical reactions and / or pressure differentials.

[0035] The eyepiece may be configured to include multiple waveguides, as described below. During the manufacture of the eyepiece, an edge sealant (e.g., a polymer) may be applied along at least a portion of the periphery of the eyepiece. The sealant may then be cured using ultraviolet (UV) light directed at the edge sealant. The eyepiece may also be manufactured to include a lamination dam that limits the wicking of the sealant material between the layers of the eyepiece to a specific depth before the sealant material has fully cured. In some examples, the edge sealant is applied to the optical device to prevent or at least reduce light leakage from the optical device and also to ensure and maintain the structure of the multilayer optical device. In some examples, the optical device is an eyepiece manufactured for use in virtual reality, augmented reality, and / or computer vision interface devices and / or to transmit image data, video data, graphic data, and / or other types of visually perceptible information to a user wearing or otherwise using the interface device. The sealant may be applied to absorb light from the eyepiece and to prevent light reflection back into the eyepiece and to prevent degradation of its optical performance.

[0036] A sealant may be applied to at least a portion of the edge of the eyepiece, wherein the application spans the entire thickness of the eyepiece and all layers of a multilayer eyepiece. Once the sealant is applied to the multilayer structure, the sealant begins to wick between the layers of the eyepiece. Therefore, curing of the sealant can begin shortly after sealant application is completed (e.g., immediately following). Various factors can contribute to the amount of wicking that occurs (e.g., wicking length), including: the specific material used for the sealant and its viscosity; a delay before curing begins; and / or variations in the material, such as the size of the air gaps between the layers in the eyepiece. For example, the smaller the air gaps between layers, the more wicking may occur due to capillary effects. In some embodiments, curing and sealant application may be synchronized, such that all portions of the sealant (e.g., all portions of the edge) may have the same or substantially the same wicking time. In some embodiments, lamination dams are arranged between the layers of the eyepiece to stop the wicking of the sealant at a specific depth, as further described below.

[0037] In some embodiments, one or more (e.g., ultraviolet) light sources (probes) may be used to cure the sealant. For example, the sealant may be a black UV-sensitive polymer that cures when exposed to UV light for a sustained period of time. The use of a sealant can enhance the optical performance of the eyepiece with respect to brightness and / or contrast, while also providing mechanical strength and structural integrity to the multilayered structure of the eyepiece.

[0038] If the sealant is applied continuously along the entire perimeter of the eyepiece without any gaps between the sealant and the lamination dam, the optical performance of the eyepiece (e.g., relative to contrast, efficiency, etc.) may degrade over time due to the accumulation of defects. Such defects can arise when chemicals generated by venting through the sealant and / or dam material react with chemicals present in the eyepiece (e.g., chemicals on the surfaces of the optical layers). These defects can accumulate over time on the optical gratings of each optical layer, leading to optical aberrations during eyepiece operation (e.g., double images, blurring, artifact images, etc.). Furthermore, in the absence of gaps, the optical layers can deform over time due to differences in trapped air gap pressure caused by variations in altitude and / or temperature. Such pressure differences can manifest between layers within the eyepiece and / or between the inside and outside of the eyepiece, and can cause substantial mechanical deformation of the eyepiece structure.

[0039] The embodiments employ one or more venting gaps through both the dam and the sealant, allowing airflow between the interior and exterior of the eyepiece. By using these gaps, the embodiments allow vented chemicals to flow to the exterior of the eyepiece, thereby reducing contamination of the optical grating as described above. The gaps also allow for the balancing of air pressure across the layers and between the interior and exterior of the eyepiece, thereby reducing or eliminating mechanical deformation caused by pressure differences over time. The gaps in the dam and sealant can be positioned substantially at the same location in the dam and sealant covering the periphery of the eyepiece to allow airflow. For example, the gaps in the sealant can be concentric with or otherwise overlap with the gaps in the dam. In some embodiments, the width of the gap in the dam can differ from the width of the gap in the sealant, as further described below, to prevent sealant from passing through the gaps in the dam and reaching the wicking inside the eyepiece.

[0040] Eyepieces with and without gaps were tested and compared, and this testing verified that using gaps helps reduce defect deposition on the grating of the optical layers, thereby improving key optical performance indicators (KPIs) such as contrast and efficiency. Through mechanical simulation of an eyepiece without a vent, it was determined that the eyepiece layers could be deformed by up to 95 micrometers by pressurizing the internal and external layers to sea level, then setting the external pressure to the air pressure at an altitude of 10,000 feet, and finally returning to sea level. This deformation can introduce crosstalk between optical layers, resulting in double images or artifact images in the optical display. The use of gaps improves eyepiece performance by reducing or preventing defect deposition and pressure-based deformation.

[0041] In some embodiments, the materials used for the lamination dam and edge sealing adhesives, as well as the surfaces used for the optical layers, may be hydrophobic to prevent additional water condensation that may occur between the layers when gaps are present. In some embodiments, the lamination dam is a curable optical adhesive applied to spacers of a specified height (e.g., 50 micrometers, but depending on the optical design). In some embodiments, the curable adhesive includes the spacer beads themselves. The spacer beads may be glass or polymer to match refractive index and structural requirements.

[0042] In some embodiments, the eyepiece comprises a suspension of polymeric adhesive and soda-lime silicate glass beads, wherein the glass beads are present to maintain an air gap and to maintain an offset between the interior and exterior of the optical device. The offset is defined by the size of the glass beads and enhances the mechanical properties of the layer by reducing warpage and bending and increasing mechanical strength. In some embodiments, the lamination dam suspension has a viscosity of 70,000 centipoise (cP) or greater at room temperature. In some embodiments, the size of the soda-lime silicate glass beads is 20 micrometers or greater.

[0043] Figure 1A schematic top view of an example eyepiece 102 according to an embodiment of the present disclosure is depicted. As shown in this example, eyepiece 102 may include various eyepiece grating regions, including an orthogonal pupil expander (OPE) region 104, an exit pupil expander (EPE) region 106, and an insertion grating (ICG) region 108. Eyepiece 102 may include a sealant 114 (also described as an edge sealant or edge sealant) surrounding at least a portion of the periphery of eyepiece 102, as described above. Eyepiece 102 may also include a laminated dam 116 (also described as a dam) disposed between the layers of eyepiece 102 to prevent wicking of sealant material that may occur before the sealant has fully cured. Eyepiece 102 may include one or more vent gaps 110 (also described as gaps) located in the sealant 114 and the dam 116, which allow airflow between the interior and exterior of eyepiece 102. Such flow allows for the venting of gases generated during the curing of the sealant and / or dam material 118, and prevents pressure differentials that could cause physical deformation of the eyepiece layer.

[0044] In some embodiments, a portion of the periphery of eyepiece 102 may be characterized as a critical region 112, which is also described as a critical optical path. Along the critical path, the presence of sealant along the edge of eyepiece 102 absorbs light and prevents optical aberrations, as described above. Therefore, gaps 110 may be positioned along the periphery at locations not within the critical region, since gaps in the critical region can cause optical aberrations due to light reflected back into the eyepiece. Eyepiece 102 may include any suitable number of gaps 110, and each gap 110 may have a suitable length. Each gap 110 may include a gap in the sealant and a gap in the dam. Gap 110 may be located at approximately the same position and length in both the dam 116 and the sealant 114 to provide sufficient airflow through both the dam 116 and the sealant 114. In some embodiments, the length of gap 110 may differ slightly between the dam 116 and the sealant 114, as further described below.

[0045] Figure 2 A schematic diagram depicting a portion of an example eyepiece 102 according to an embodiment of the present disclosure is shown. Figure 2 The specific dimensions and tolerances shown (in millimeters) are provided as examples, and the embodiments are not limited to the example dimensions and tolerances shown. The dashed lines indicate variations in the positioning of the gap 110 in the sealant 114 and the dam 116. Figure 2An embodiment is shown in which the eyepiece 102 includes one or more gaps 110 that allow airflow through both the sealant 114 and the dam 116. In some embodiments, as shown in this example, the length of the gap 110 through the sealant 114 is different from the length of the gap 110 through the dam 116. For example, the length of the gap 110 through the dam 116 may be less than the length of the gap 110 through the sealant 114. This length difference can be used to suppress wicking of the sealant 114 into the interior of the eyepiece 102 through the gap in the dam 116. Also as shown, the gap 110 in the sealant 114 may begin at a location outside the critical area around the eyepiece.

[0046] In one example, the edge seal and lamination dam gap are concentric at a distance of 4 mm from the top corner of the OPE. The vent gap size can be 3 mm and can vary between a minimum of 1 mm and a maximum of 5 mm. The lamination vent gap can be positioned with an accuracy specified as ±1 mm, and the edge seal vent gap can be positioned with an accuracy specified as ±2 mm. In some embodiments, the edge seal vent gap size can be determined based on the lamination dam vent gap size. The edge seal vent gap can have a 1 mm safety zone from the edge of the lamination dam vent gap to prevent sealant leakage into the dam vent gap. The edge seal can be maintained within critical areas or critical optical paths (e.g., with endpoints defined by the intersection of the extension line of the OPE grating and the glass edge as depicted by the dotted line), thereby avoiding gaps in critical areas.

[0047] Figure 3 A schematic cross-sectional view 300 of an example optical device 102 (e.g., an eyepiece) according to an embodiment of the present disclosure is depicted. The view shown is a cross-section of the example eyepiece. As shown, the eyepiece may include multiple layers 302, each layer providing a waveguide for light in a specific wavelength band. For example, different layers may be designed to guide red, green, or blue light. An edge sealant 114 may be applied to the edge of the eyepiece as shown to attempt to prevent light leakage 310 from the inside of the eyepiece to the outside in a lateral direction across the edge. The edge sealant 114 also prevents light reflection back into the eyepiece. The edge sealant 114 may be applied to have a suitable thickness 306 and may penetrate (by wicking) into the eyepiece, between the layers 302, to a suitable depth 308. The eyepiece may be constructed of multiple layers (e.g., high-refractive-index) of glass stacked in a layered manner. A dam 116 may also be used to stop the wicking of the sealant 114. As shown in the example, the dam 116 can be arranged between layers 302 at a specific depth 308 relative to the edge of the eyepiece 102 so that the wicking of the sealant 114 stops at depth 308.

[0048] The ventilation gaps described herein can be used in any suitable type of optical device. In some examples, the eyepiece can be at least partially made using a Molecular Imprint. TM Developed jet and flash embossing technology (J-FIL) TM J-FIL technology can be used to create diffraction gratings on the glass layers of an eyepiece to create a waveguide display. Each layer can be a thin glass layer with a polymer grating created on its surface using J-FIL. The diffraction grating provides the basic working function of the eyepiece. Once the diffraction grating is formed on a large, wide glass layer, the glass layer can be laser-cut into the shape of the eyepiece. Each glass layer can be a different color and can have multiple depth planes. A larger number of planes can provide a better virtual experience for the user using the eyepiece. Layers can be stacked using sealant polymers (e.g., dots or lines), and the entire stack can be sealed with sealant. Air gaps between layers can be preserved for the optical performance of the eyepiece. The gaps between layers can have controlled dimensions (e.g., substantially uniform width). Edge sealant polymers can be applied around the edges of the layered structure to seal the stack and air gaps from the external environment. Edge sealant also provides a physical lock to ensure the mechanical integrity of the structure while preventing external particle contamination and / or reducing the possibility of moisture accumulation. Without this seal, these layers may separate and delaminate from each other. The gaps between the layers can have any suitable width to achieve the desired optical function.

[0049] The use of a sealant enables the creation of a high-contrast eyepiece by absorbing stray light impacting the edges of the eyepiece layers. The sealant also provides structural integrity, for example, "locking in" mechanical clearances and coplanarity of the eyepiece. The eyepiece may have any suitable number of layers 302 of glass or other materials, and each layer may act as a waveguide to allow light of various frequencies to pass through. Layers may be configured for specific wavelengths to propagate specific colors of light, and the eyepiece may be configured for specific optical power to create multiple depth planes at which light can be sensed by the waveguides. For example, a first set of waveguide layers may include layers for red, green, and blue light at a first depth plane, and a second set of waveguide layers may include a second set of layers for red, green, and blue light corresponding to a second depth plane. The order of colors may be arranged differently in different depth planes to achieve the desired optical effect in the eyepiece. In some embodiments, a single (e.g., blue) layer may cover multiple depth planes. In some examples, the edge sealant may be an adhesive, resin, polymer sealant, ink, and / or other adhesive material. The edge sealant may be black. Darkening the edges of multi-layer eyepieces can cause absorption of light hitting the edges and / or provide reduced reflection of light striking the edges.

[0050] Figure 4 An example dam arrangement in an eyepiece according to an embodiment of this disclosure is depicted. Units shown are in micrometers. For example, the thickness of the sealant from the edge of the glass can be 80-150 micrometers, and the wicking depth of the sealant can be 350 micrometers until the dam stops the wicking. The dam can be 500 micrometers wide and separated from the grating boundary of the eyepiece by a gap 650 micrometers wide. The distance between the edge of the glass and the grating boundary can be 1500 micrometers (1.5 mm). Other suitable dimensions may also be used.

[0051] Figure 5 A schematic diagram illustrating example deformations of the layers in eyepiece 500, such as without a vent. For example, the eyepiece may include 11 layers: a 250-micron optical layer, a 25-micron pitch, nine depth planes, and two cover glass layers. Under test conditions, the environment inside and outside the eyepiece was initially pressurized to sea-level pressure. The external air pressure was set to the pressure at an altitude of 10,000 feet and then returned to sea-level pressure. As a result, the pressure difference caused out-of-plane deformation of the layers in the eyepiece, up to 95 microns.

[0052] Figure 6A and 6B The images shown are scanning electron microscope (SEM) images of eyepiece defects with and without a vent, according to embodiments of the present disclosure. Figure 6A In the example, image 600 shows a scanning electron microscope (SEM) image of the eyepiece area (e.g., the area between OPE and EPE) after a 1000-hour heat and humidity test in which the eyepiece was exposed to 65 degrees Celsius and 95% relative humidity. Figure 6B Image 602 shows a SEM image of the eyepiece region, including the vent, in an eyepiece subjected to similar test conditions. As shown, the presence of the vent significantly reduces and / or eliminates the incidence of contamination defects in the eyepiece.

[0053] While this specification contains numerous specific details, these should not be construed as limiting the scope of this disclosure or the claims, but rather as examples of features associated with particular embodiments. Certain features described herein in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, although features may be described as functioning in certain combinations and even initially claimed in this way, one or more features from a claimed combination may be removed from the combination in some examples, and the claimed combination may be for sub-combinations or variations thereof.

[0054] Several embodiments have been described. However, it will be understood that various modifications can be made without departing from the spirit and scope of this disclosure. For example, various structures shown above can be used in which elements are rearranged, positioned differently, oriented differently, added, and / or removed. Therefore, other embodiments are within the scope of the appended claims.

Claims

1. An optical device, comprising: Multiple optical layers; An edge sealant disposed across the plurality of optical layers along the edge of the optical device, wherein one or more sealant gaps exist in the edge sealant; as well as Laminated dams are arranged between each pair of adjacent optical layers to prevent wicking of the edge sealant between the optical layers and at a distance from the edge of the optical device. One or more dam gaps are present in the laminated dams at one or more locations along the edge, each of these locations corresponding to the location of a corresponding sealant gap, to allow airflow between the interior and exterior of the optical device through the one or more sealant gaps and the one or more dam gaps. The one or more sealant gaps are located outside a critical region at the edge of the optical device; the critical region is part of the periphery of the optical device; and the edge sealant absorbs light along the critical region. Wherein, one of the one or more sealant gaps has a length along the edge of the optical device that exceeds the length of the corresponding dam gap, wherein one or more of the surfaces of the edge sealant, the laminated dam, and one of the plurality of optical layers are at least partially composed of a hydrophobic material.

2. The optical device according to claim 1, wherein, The edge sealant is applied at least partially to the critical area.

3. The optical device according to claim 1, wherein, Along the edge of the optical device, at least one of the one or more sealant gaps at least partially overlaps with a corresponding one of the one or more dam gaps.

4. The optical device according to claim 1, wherein, At least one of the one or more sealant gaps is concentric with a corresponding one of the one or more dam gaps.

5. The optical device according to claim 1, wherein: The edge sealant includes at least two sealant gaps; and The layered dam includes at least two dam gaps.

6. The optical device according to claim 1, wherein, The plurality of optical layers includes at least three optical layers.

7. The optical device according to claim 6, wherein, The at least three optical layers include a layer for guiding red light, a layer for guiding green light, and a layer for guiding blue light.

8. The optical device according to claim 1, wherein, The edge sealant absorbs ultraviolet radiation.

9. The optical device according to claim 1, wherein, At least one of the plurality of optical layers, the optical layer includes at least one of the following: an orthogonal pupil expander region, an exit pupil expander region, and a grating coupling region.

10. The optical device according to claim 1, wherein, The one or more sealant gaps and the one or more dam gaps allow airflow between the interior and exterior of the optical device.

11. The optical device according to claim 1, wherein, The edge sealant prevents light leakage in the lateral direction from the inside to the outside of the optical device through the edge of the optical device.

12. The optical device according to claim 1, wherein, The edge sealant prevents light from being reflected into the interior of the optical device.

13. The optical device according to claim 1, wherein, The thickness of the edge sealant is in the range of 430 micrometers to 500 micrometers.

14. The optical device according to claim 1, wherein, The edge sealant has a thickness of 350 micrometers between the edge of the optical device and the laminated dam.

15. The optical device according to claim 1, wherein, The width of the laminated dam is 500 micrometers.

16. An eyepiece comprising the optical device of claim 1.

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