A multi-plane optical see-through head mounted display design for augmented reality applications

Abstract

Augmented reality (AR) display technology greatly enhances users' perception of and interaction with the real world by superimposing a computer‐generated virtual scene on the real physical world. The main problem of the state‐of‐the‐art 3D AR head‐mounted displays (HMDs) is the accommodation‐vergence conflict because the 2D images displayed by flat panel devices are at a fixed distance from the eyes. In this paper, we present a design for an optical see‐through HMD utilizing multi‐plane display technology for AR applications. This approach manages to provide correct depth information and solves the accommodation‐vergence conflict problem. In our system, a projector projects slices of a 3D scene onto a stack of polymer‐stabilized liquid crystal scattering shutters in time sequence to reconstruct the 3D scene. The polymer‐stabilized liquid crystal shutters have sub‐millisecond switching time that enables sufficient number of shutters to achieve high depth resolution. A proof‐of‐concept two‐plane optical see‐through HMD prototype is demonstrated. Our design can be made lightweight, compact, with high resolution, and large depth range from near the eye to infinity and thus holds great potential for fatigue‐free AR HMDs.

Multiplane displays based on liquid crystals for AR applications

“…Wu et al used a tunable PB LC lens that can achieve a response time as fast as 0.7 ms in their AR display system . We have fabricated PSLC shutters that could be switched between transparent and scattering states with submillisecond response time, which enables relatively large number of image planes …”

“…States of polymer stabilized liquid crystal (PSLC) films with applied voltage on and off. A and B, a normal mode PSLC (NPSLC) film with applied voltage on and off, respectively . C and D, a reverse mode PSLC (RPSLC) film with applied voltage on and off, respectively…”

“…The key components of multiplane displays using the time‐multiplexing method are fast tunable optical devices, such as liquid lens, deformable mirror, and liquid crystal (LC) devices . For instance, Hua et al realized a multiplane optical see‐through (OST) AR display utilizing a tunable liquid lens.…”

“…Tunable LC lenses (eg, LC refractive lens and LC Pancharatnam‐Berry [PB] lens) are employed in AR displays, to control the distance of virtual images by varying their focal lengths. And in some displays, multiple LC scattering shutters are used as the display medium …”

“…In the following sections, we first introduce the working principle of multiplane AR displays and then focus on two types of multiplane AR displays based on LCs. The first one is realized by sequentially switching fast polymer stabilized LC (PSLC) scattering films to form the multiplane display medium . The second one is implemented by utilizing polarization selective CLC reflective devices.…”