ABSTRACT
This chapter discusses the technology performance characteristics of both refractive and wide field-of-view head-up display optics. Head-up display (HUD) systems are electro-optical devices that present attitude, navigation, guidance, targeting, and other information into the pilot’s forward field of regard through the aircraft windshield. The design of refractive HUD systems using spectrally insensitive dielectric combiners entails a trade-off between the real-world photopic transmission through, and the cathode-ray tube light reflection from, the combiner. The performance of holographic HUD combiners is determined from the hologram spectral and angular bandwidths and the peak diffraction efficiency. The holographic emulsion used in essentially all holographic HUD combiner elements in production today is dichromated gelatin. In refractive optics HUD applications, flat wavelength-selective holographic combiners are used to enhance the photometric characteristics of the display. The most important attributes of holographically manufactured combiner coatings in HUDs have to do with the photometric performance characteristics.
