PSS printing passes. A novel transparent touch sensor fabricated with an all-inkjet-printing method is demonstrated for the first time. This process holds industrially viable potential to fabricate transparent touch sensors with an inkjet printing technique on both rigid and flexible substrates for a wide range of applications.

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Two-dimensional arrays of microlenses can be used in wearable display applications as numerical aperture expanders or exit-pupil expanders (EPEs) to increase the size of the display exit pupil. A novel EPE approach that uses two microlens arrays (MLAs) is presented. The approach is based on cascading two identical microlens arrays spaced precisely at one focal-length distance with submicrometer registration tolerances relative to each other. The ideal MLA for this application requires a 100% fillfactor, sharp seams between microlenses, and a perfect spherical profile. We demonstrate a dual-MLA-based EPE that produces excellent exit-pupil uniformity and better than 90% diffraction efficiency for all three wavelengths in a color-display system. Two-MLA registration is performed with submicrometer precision by use of far-field alignment techniques. Fourier optics theory is used to derive the analytical formulas, and physical optics beam propagation is used for numerical computations. Three MLA fabrication technologies, including gray-scale lithography, photoresist reflow, and isotropic etching, are evaluated and compared for an EPE application.

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Retinal Scanning Display (RSD) is a near-to-eye scanned beam display technology. An exit pupil expander (EPE) or numerical aperture (NA) expander is used in RSDs to create a large display exit pupil. A novel EPE approach that uses two microlens arrays (MLA) is presented in this paper. The approach is based on cascading two identical microlens arrays spaced precisely at one focal length distance with sub-micron registration tolerances relative to each other. We demonstrated a dual MLA based EPE that produced excellent exit pupil uniformity and better than 90% diffraction efficiency for all three wavelengths in a color display system. Registration was performed with sub-micron precision using farfield alignment techniques. Both numerical and experimental results are presented, and three fabrication technologies: grayscale lithography, photoresist reflow, and isotropic etching, are compared.