Split-Lohmann Multifocal Displays

Abstract

This work provides the design of a multifocal display that can create a dense stack of focal planes in a single shot. We achieve this using a novel computational lens that provides spatial selectivity in its focal length, i.e, the lens appears to have different focal lengths across points on a display behind it. This enables a multifocal display via an appropriate selection of the spatially-varying focal length, thereby avoiding time multiplexing techniques that are associated with traditional focus tunable lenses. The idea central to this design is a modification of a Lohmann lens, a focus tunable lens created with two cubic phase plates that translate relative to each other. Using optical relays and a phase spatial light modulator, we replace the physical translation of the cubic plates with an optical one, while simultaneously allowing for different pixels on the display to undergo different amounts of translations and, consequently, different focal lengths. We refer to this design as a Split-Lohmann multifocal display. Split-Lohmann displays provide a large étendue as well as high spatial and depth resolutions; the absence of time multiplexing and the extremely light computational footprint for content processing makes it suitable for video and interactive experiences. Using a lab prototype, we show results over a wide range of static, dynamic, and interactive 3D scenes, showcasing high visual quality over a large working range.

Impact of focus cue presentation on perceived realism of 3-D scene structure: Implications for scene perception and for display technology

“…Some applications may require only a small range of depths to be presented, however, potentially allowing the same number of focal planes to be spaced more closely. Also, novel approaches continue to be developed, including a recent study that used a locally addressable phase modulator to create different focal distances in different spatial regions of a conventional display, with reasonably high resolution in focal depth ( Qin, Chen, O'Toole, & Sankaranarayanan, 2023 ). Note, however, this approach is not strictly a multiple-focal-planes display, in that it cannot present multiple focal distances along a single line of sight ( Akeley et al, 2004 ).…”