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Applied Optics

Applied Optics


  • Vol. 44, Iss. 23 — Aug. 10, 2005
  • pp: 4930–4936

Microlens-array-based exit-pupil expander for full-color displays

Hakan Urey and Karlton D. Powell  »View Author Affiliations

Applied Optics, Vol. 44, Issue 23, pp. 4930-4936 (2005)

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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% fill factor, 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.

© 2005 Optical Society of America

OCIS Codes
(050.1950) Diffraction and gratings : Diffraction gratings
(070.2580) Fourier optics and signal processing : Paraxial wave optics
(220.4000) Optical design and fabrication : Microstructure fabrication
(230.3990) Optical devices : Micro-optical devices
(350.3950) Other areas of optics : Micro-optics

Original Manuscript: October 18, 2004
Revised Manuscript: March 17, 2005
Manuscript Accepted: March 21, 2005
Published: August 10, 2005

Hakan Urey and Karlton D. Powell, "Microlens-array-based exit-pupil expander for full-color displays," Appl. Opt. 44, 4930-4936 (2005)

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