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Proceedings Paper

Low-cost color LCD helmet display
Author(s): Roger Leinenwever; Leonard G. Best; Bryce J. Ericksen
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Paper Abstract

The goal of this helmet-mounted display (HMD) project was development and demonstration of a low-cost color display incorporating see-through optics. A full field-of-regard visual presentation was to be provided through the use of a head-tracker system and the HMD was to be suitable for use with low-cost cockpit trainers. The color imaging devices selected for the project are commercially available liquid crystal display (LCD) panels. The LCDs are 3.0 inch (diagonal) thin film transistor (TFT) types using a delta format for the red, green, blue (RGB) matrix. Fiber optic light panels mounted behind the LCDs provide a cool light source of greater than 3400 foot-lamberts (ft-L). Approximately 3 percent of the applied light source is emitted by the LCD image source. The video displayed is in a 3:4 format representing a 30 degree(s) vertical by 40 degree(s) horizontal biocular instantaneous field-of-view (IFOV) visual image from a graphic image generation system and is controlled in a full field of regard based on positional information from a head-tracker system. The optical elements of the HMD are designed as an exit pupil forming, see-through system and require the eye to be in a 15 mm volume for viewing the scene. The beam splitting function of the optics allows the user to see through the optics for reading cockpit instrumentation, while viewing outside the cockpit reveals the out-the-window (OTW) scene. The optic design allows for the IFOV to be displayed through a set of field lens, relay lens, folding mirror, beam splitter and spherical mirror system. The beam splitters and spherical mirrors for both optical paths are coated for approximately 50 percent transmission and reflectance. This approach, combined with the losses through the rest of the optical path, provides a theoretical maximum of 10.9 percent of the LCD image source intensity arriving at the eye. Initial tests of image intensity at the eye for a full white scene have measured at approximately 11 ft-L.

Paper Details

Date Published: 30 October 1992
PDF: 4 pages
Proc. SPIE 1695, Helmet-Mounted Displays III, (30 October 1992);
Show Author Affiliations
Roger Leinenwever, GE Government Services (United States)
Leonard G. Best, GE Government Services (United States)
Bryce J. Ericksen, Visual Display Consultant (United States)

Published in SPIE Proceedings Vol. 1695:
Helmet-Mounted Displays III
Thomas M. Lippert, Editor(s)

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