An ultra-light and compact design and implementation of head-mounted projective displays

Head-mounted projective displays (HMPD) have been recently proposed as an alternative to conventional eyepiece-type head-mounted displays. HMPDs consist of a pair of miniature projection lenses and displays mounted on the helmet and retro-reflective sheeting materials placed strategically in the environment. Its novel concept and properties suggest solutions to part of the problems of state-of-art visualization devices and make it extremely suitable for multiple-user collaborative applications and wearable systems. In this paper, a brief review of conventional visualization techniques is followed by an extensive discussion of HMPD technology, which includes a summary of its features and a comparison with conventional head-mounted displays (HMDs), projection-based displays, and HMPDs. An ultra-light and compact design (i.e. 8g) of a projection lens system using diffractive optical element (DOE) as well as plastic components for a HMPD is presented. Through the usage of fast prototyping technology, a compact stereoscopic head-mounted prototype with weight less than 700 grams was implemented, and optomechanical adjustments and ergonomic considerations are discussed. Finally, the motivated application in multiuser tele-collaboration is described.