Digitally switchable multi-focal element for wearable displays

Xuan Wang, Hong Hua

Research output: Chapter in Book/Report/Conference proceedingConference contribution


An innovative concept is proposed for an optical element which offers the capability of rapidly switching the optical power of the system among multiple foci. The switchable multifocal element consists of a custom-designed freeform lens offering multiple discrete foci and a programmable high-speed liquid crystal shutter (LCS). The freeform lens is divided into patterned zones, through which multiple distinct foci are produced. The LCS consists of patterned zones corresponding to those zones of the freeform lens, which can be programmably switched on and off. By combining the multi-focal freeform lens and the LCS in a time-multiplexed fashion, a switchable multifocal element with high-speed, large aperture and large range of tunable power was achieved. The multifocal element also meets the other requirement of an ideal tunable optical element such as low-voltage control, robustness, and compactness. A proof-of-concept twofocal head mounted display was designed to demonstrate one application of the new switchable multifocal element. The design can provide a FOV of 40 degrees and angular resolution of 1 arc minutes in visual space in an 8mm by 8mm exit pupil.

Original languageEnglish (US)
Title of host publicationOptical Design Challenge 2019
EditorsChristophe Peroz, Bernard C. Kress
ISBN (Electronic)9781510627468
StatePublished - 2019
EventOptical Design Challenge 2019 - San Francisco, United States
Duration: Feb 3 2019 → …

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceOptical Design Challenge 2019
Country/TerritoryUnited States
CitySan Francisco
Period2/3/19 → …


  • Multi-focal
  • freeform optics
  • switchable element

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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