Embodiments of the present disclosure generally relate to optical devices. More specifically, embodiments described herein provide for the introduction of an encapsulation material into an optical device formed with a same thickness distribution at one or more eyepiece areas across a substrate.
Virtual reality is generally considered to be a computer generated simulated environment in which a user has an apparent physical presence. A virtual reality experience can be generated in 3D and viewed with a head-mounted display (HMD), such as glasses or other wearable display devices that have near-eye display panels as optical devices to display a virtual reality environment that replaces an actual environment.
Augmented reality, however, enables an experience in which a user can still see through the optical devices of the glasses or other HMD device to view the surrounding environment, yet also see images of virtual objects that are generated for display and appear as part of the environment. Augmented reality can include any type of input, such as audio and haptic inputs, as well as virtual images, graphics, and video that enhances or augments the environment that the user experiences. As an emerging technology, there are many challenges and design constraints with augmented reality.
Having the same thickness distribution at one or more eyepiece areas across a substrate alleviates substrate-to-substrate variation. To facilitate achievement of the same thickness distribution, an index-matched layer is patterned. The optical device is subsequently patterned. Accordingly, what is needed in the art are improved methods of patterning the index-matched layer.
In one embodiment, an optical device is provided. The optical device includes a substrate having a substrate depth defined by a top surface of the substrate and a bottom surface of the substrate. The substrate depth varies across the optical device. The optical device includes an index-matched layer disposed over the substrate. The index-matched layer has a layer depth defined by an upper surface of the index-matched layer and a lower surface of the index-matched layer. The layer depth varies across the optical device. The optical device includes a plurality of optical device structures formed over the index-matched layer. The adjacent structure top surfaces of the plurality of optical device structures are planar. The optical device further includes an encapsulation material disposed between the plurality of optical device structures and the index-matched layer.
In another embodiment, a method of forming an optical device is provided. The method includes disposing an index-matched layer over a substrate. The substrate has a substrate depth defined by a top surface of the substrate and a bottom surface of the substrate. The substrate depth varies across the optical device such that a lower surface of the index-matched layer varies according to the substrate depth. The method includes patterning the index-matched layer. The index-matched layer and the substrate define a target thickness distribution that varies across the substrate. The method further includes disposing an encapsulation layer over an upper surface of the index-matched layer. The method includes disposing an optical device film over the encapsulation layer. The method further includes patterning a plurality of optical device structures in the optical device film. The adjacent structure top surfaces of the plurality of optical device structures are planar. A device height defined from the bottom surface to each of the structure top surfaces is constant.
In another embodiment, a method of forming an optical device is provided. The method includes disposing an index-matched layer over a substrate. The substrate has a substrate depth defined by a top surface of the substrate and a bottom surface of the substrate. The substrate depth varies across the optical device such that a lower surface of the index-matched layer varies according to the substrate depth. The method includes patterning the index-matched layer. The index-matched layer and the substrate define a target thickness distribution that varies across the substrate. The method includes disposing an encapsulation material into the index-matched layer to form an encapsulation material gradient. A concentration of the encapsulation material decreases as a distance from an upper surface of the index-matched layer is increased. The method includes disposing an optical device film over the encapsulation material. The method further includes patterning a plurality of optical device structures in the optical device film. The adjacent structure top surfaces of the plurality of optical device structures are planar. A device height defined from the bottom surface to each of the structure top surfaces is constant.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of scope, as the disclosure may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Embodiments of the present disclosure generally relate to optical devices. More specifically, embodiments described herein provide for the introduction of an encapsulation material into an optical device formed with a same thickness distribution at one or more eyepiece areas across a substrate.
In one embodiment, which can be combined with other embodiments described herein, the optical devices 200A or 200B are waveguide combiners, such as augmented reality waveguide combiners. In another embodiment, which can be combined with other embodiments described herein, the optical devices 200A or 200B are flat optical devices, such as metasurfaces.
The substrate 100 and the index-matched layer 108 may be formed from any suitable material, provided that the substrate 100 can adequately transmit light in a desired wavelength or wavelength range and can serve as an adequate support for the optical devices 200A or 200B. The substrate 100 may be a material including, but not limited to, amorphous dielectrics, non-amorphous dielectrics, crystalline dielectrics, silicon oxide, polymers, and combinations thereof. In some embodiments, which may be combined with other embodiments described herein, the substrate 100 includes a transparent material. In one example, the substrate 100 includes silicon (Si), silicon dioxide (SiO2), fused silica, quartz, silicon carbide (SiC), germanium (Ge), silicon germanium (SiGe), indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), sapphire, or combinations thereof. The index-matched layer 108 is a nanoparticle material. For example, the index-matched layer 108 is titanium oxide (TiO2) or zirconium oxide (ZrO2). In one example, the substrate 100 and the index-matched layer 108 are different materials. In another example, the substrate 100 and the index-matched layer 108 are the same material.
The substrate 100 and the index-matched layer 108 form a target thickness distribution 116. The target thickness distribution 116 is the local thickness distribution that has been determined to be replicated at each of the eyepiece areas 101. The target thickness distribution 116 is defined by the distance between the upper surface 102 of the index-matched layer 108 and the bottom surface 111 of the substrate 100 across the eyepiece area 101. In one example, the target thickness distribution 116 is a linear distribution. In another example, the target thickness distribution 116 is a nonlinear distribution. The target thickness distribution 116 varies across the substrate 100 of the optical device 200A or 200B. In one embodiment, which can be combined with other embodiments described herein, the target thickness distribution 116 is in the eyepiece areas 101 and the inactive areas 104. In another embodiment, which can be combined with other embodiments described herein, the target thickness distribution 116 is only in the eyepiece areas 101. In some embodiments, which can be combined with other embodiments described herein, the top surface 110 of the substrate 100 is planar relative to the bottom surface 111 of the substrate 100.
The substrate 100 includes a substrate depth 214. The substrate depth 214 is defined as the distance between the top surface 110 and the bottom surface 111 of the substrate 100. The substrate depth 214 varies across the optical device 200A or 200B. The index-matched layer 108 includes a layer depth 216. The layer depth 216 is defined as the distance between the upper surface 102 of the index-matched layer 108 and the top surface 110 of the substrate 100. The layer depth 216 varies across the optical device 200A or 200B. The index-matched layer 108 is disposed over the substrate 100 such that the varying substrate depth 214 defines where the lower surface 103 of the index-matched layer 108 is positioned. As such, the positioning of the lower surface 103 varies according to the substrate depth 214.
The target thickness distribution 116 is engineered to improve the performance of the optical devices 200A or 200B formed thereon. The target thickness distribution 116 is the same in at least each eyepiece area 101 of the substrate 100 and the index-matched layer 108. Methods described herein will provide for the target thickness distribution 116 to be achieved in at least each eyepiece area 101. The target thickness distribution 116 is not limited to the target thickness distribution 116 shown in
In one embodiment, as shown in
In another embodiment, as show in
In one example, the optical device layer 204 is disposed over the encapsulation layer 202 (shown in
The plurality of optical device structures 208 may be nanostructures having sub-micron dimensions, e.g., nano-sized dimensions. The plurality of optical device structures 208 may correspond to an input coupling grating or an output coupling grating of the optical devices 200A or 200B. The optical devices 200A or 200B are not limited to the number of the plurality of optical device structures 208 shown in
The optical devices 200A or 200B can undergo processing steps during and after fabrication. For example, when patterning the optical device layer 204 to form the optical devices 200A or 200B, the index-matched layer 108 and the substrate 100 can be damaged. The encapsulation layer 202 (shown in
At operation 301, as shown in
At operation 302, as shown in
At operation 303, as shown in
In one embodiment, which can be combined with other embodiments described herein, the target thickness distribution 116 is formed with a lithography process. The lithography process is a gray-tone lithography process. The gray-tone lithography includes patterning a gray-tone resist (not shown) with a resist thickness distribution that corresponds to the target thickness distribution 116. The gray-tone resist is developed with a lithography process, such as photolithography and digital lithography. In another embodiment, which can be combined with other embodiments described herein, the target thickness distribution 116 is formed with an inkjet printing process. In embodiments where the inkjet printing process is utilized, the index-matched layer 108 is directly deposited onto the substrate 100 to have the target thickness distribution 116. Direct deposition of the appropriate amount of the index-matched layer 108 allows for the formation of the target thickness distribution 116.
By utilizing gray-tone lithography and inkjet printing processes to apply the index-matched layer 108, maskless application and patterning of the index-matched layer 108 to form the target thickness distribution 116 is possible. By forming the target thickness distribution 116 in each of the eyepiece areas 101, variation of substrate thickness is reduced. As such, improvement of optical device quality and fabrication time are obtained. For example, further control of the propagation of light through the optical devices is possible due to the consistency of the target thickness distribution 116 across the eyepiece areas 101.
At operation 304, as shown in
At operation 305, as shown in
In summation, embodiments described herein provide for the introduction of an encapsulation material into an optical device formed with a same thickness distribution at one or more eyepiece areas across a substrate. The target thickness distribution formed in at least each eyepiece area reduces variation of substrate thickness from substrate to substrate. As such, improvement of optical device quality and fabrication time are obtained. Forming the target thickness distribution in the substrate and the index-matched layer with maskless patterning such as gray-tone lithography and inkjet printing eliminates subsequent processing steps to achieve the target thickness distribution. As such, cost and fabrication complexity are reduced. The materials compatible with the gray-tone lithography and inkjet printing processes are sensitive to various wet processing, high-temperature processing, vacuum processing, and/or plasma processing. As such, providing encapsulation material between the optical device layer and the index-matched layer will protect the index-matched layer from damage and improve overall performance of the optical device.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow
This application claims benefit of and priority to U.S. Application No. 63/408,410, filed Sep. 20, 2022, the entire contents of which are incorporated herein by reference.
Number | Date | Country | |
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63408410 | Sep 2022 | US |