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Proceedings Paper

A novel approach to freeform optimization: designing an eye-tracking augmented reality system using grid-based sag optimization
Author(s): Zachary Derocher; Shawn Gay; Ken Moore
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Paper Abstract

As manufacturing capabilities have developed, the potential to create complex geometries for optical elements of a variety of materials has become a reality. Under these conditions, freeform optical components have become more prevalent in the industry, and have allowed a new class of optical systems to be engineered. In the past, freeforms have commonly been described parametrically for optimization, which in some cases limits their flexibility and utility. In this paper we demonstrate a novel freeform design methodology which uses a grid-based sag definition to serve as an alternative to polynomial coefficient optimization. The OpticStudio TrueFreeForm model allows direct optimization of sag values at grid points across the surface to enable spatially-selective surface sag optimization. Here, a case study is presented on the effectiveness of TrueFreeForm optimization in the design of freeform optical surfaces for use in modern augmented reality/virtual reality (AR/VR) optical systems. We demonstrate the flexibility and advantages of grid sag optimization and discuss key implementation considerations in the context of a freeform wedge prism system as might be found in an AR headset. In particular we demonstrate, via sub-aperture grid sag optimization, the integration of an eye-tracking subsystem into the AR wedge prism. An average MTF of 0.446 at 40 lp/mm is achieved in the user pupil imaging portion of the eye-tracking system, while introducing no degradation in the nominal performance of the AR visual display system.

Paper Details

Date Published: 21 June 2019
PDF: 10 pages
Proc. SPIE 11062, Digital Optical Technologies 2019, 110620E (21 June 2019); doi: 10.1117/12.2526096
Show Author Affiliations
Zachary Derocher, Zemax, LLC (United States)
Shawn Gay, Zemax, LLC (United States)
Ken Moore, Zemax, LLC (United States)

Published in SPIE Proceedings Vol. 11062:
Digital Optical Technologies 2019
Bernard C. Kress; Peter Schelkens, Editor(s)

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