Portable waveguide display system with a large field of view by integrating freeform elements and volume holograms.

Jian Han,Yongtian Wang,Xincheng Yao,Juan Liu

doi:10.1364/oe.23.003534

Jian Han, Yongtian Wang + Show 2 more

Open Access

https://doi.org/10.1364/oe.23.003534

Copy DOI

Abstract

A compact waveguide display system integrating freeform elements and volume holograms is presented here for the first time. The use of freeform elements can broaden the field of view, which limits the applications of a holographic waveguide. An optimized system can achieve a diagonal field of view of 45° when the thickness of the waveguide planar is 3mm. Freeform-elements in-coupler and the volume holograms out-coupler were designed in detail in our study, and the influence of grating configurations on diffraction efficiency was analyzed thoroughly. The off-axis aberrations were well compensated by the in-coupler and the diffraction efficiency of the optimized waveguide display system could reach 87.57%. With integrated design, stability and reliability of this monochromatic display system were achieved and the alignment of the system was easily controlled by the record of the volume holograms, which makes mass production possible.

Highlights

With the prosperity of augmented reality (AR) technology in navigation, education, entertainment, military operations, and biomedical applications [1,2], portable see-though displays are playing indispensable roles
For a waveguide display based on diffraction theory, Nokia [32,33,34], Konica Minolta [35], Sony [36] and BAE Systems [37,38,39] corporations have used diffractive optical elements (DOEs) or holographic optical elements (HOEs) to develop their waveguide display systems
The waveguide display system (WGDS) presented in this paper consisted of three parts, as is shown in Fig. 1, which are freeform elements (FFEs) in-coupler used to collimate and amplify the image from the microdisplay, an optical waveguide to guide light in the off-axis direction, and volume holograms that provided two optical paths to diffract the virtual image from the micro-display as well as to transmit external light

Summary

Introduction

With the prosperity of augmented reality (AR) technology in navigation, education, entertainment, military operations, and biomedical applications [1,2], portable see-though displays are playing indispensable roles. The advantages of a waveguide display system (WGDS) have attracted the interest of many researchers and have become a topic of great interest Some corporations, such as Lumus [25], Epson [26], Google [27], and Optinvent [28], have released products based on geometrical waveguides. The other three companies employed volume holograms (VHs) in the display systems, where the feature sizes of the VHs could reach nanometers by holographic recording and the FOV could be enlarged. We describe the design of a portable WGDS that employed the integration of volume holograms and freeform elements It is a monochromatic display, where freeform element works as both an in-coupler to directly couple the image source into the waveguide and a collimator to convert the spherical waves into plane waves, and the volume hologram served as an out-coupler. This efficiency can theoretically be raised to 87.57%

General description

Specifications of an in-coupler

Principles of the out-coupler

Findings

Discussion of the configuration

Conclusion