Proceedings Article | 1 May 1992
KEYWORDS: Holograms, Holography, Reflection, Modulation, Heads up displays, Holographic materials, Tolerancing, Holographic optical elements, Image quality, Glasses
There is increasing interest in head-up-displays (HUDs) for automotive use. A number of technologies could be employed for the combiner function including plain glass reflection, dielectric enhancement, and holography. This paper will consider the potential role for conformal holography as the combiner element by initially reviewing the system requirements from an optical design view, how these differ significantly from an avionic HUD, and how they relate to material characteristics and process features. This will involve a consideration in some detail of the effects of specified hologram properties and lamination features on the optical performance and image characteristic of a car HUD. In particular, we shall examine such features as hologram efficiency, bandwidth, tuning position, environmental stability, tolerances, and film lamination effects and how these may influence the key optical characteristics of the image, i.e., distortions, blur, brightness, double imaging (separation and contrast) outside world view, etc.. A theoretical model based on Kogelnik coupled wave theory will be used to illustrate the various tradeoffs between hologram properties and process, image features, and display characteristics (bandwidth, polarization, etc.). This analysis will be related to properties of currently available holographic materials with reference to recent experimental work.
