Visor projected helmet mounted displays technology and applications

Abstract

Helmet Mounted Sight and Display systems are now in service in military aircraft. Although these systems share some common features with ground based `virtual reality' systems, the military cockpit environment and the application they are used for, dictate a different approach in the design, development and qualification for military use. The primary function of the Aircrew helmet is to protect the pilot. The advent of helmet mounted displays places additional constraints on the helmet which is now an important element of the cockpit displays system, providing weapon aiming, and other information to the pilot. The design of HMDs for the military cockpit environment is therefore a demanding task if the operational benefits are to be realised without affecting pilot safety. Many designs now use the helmet visor as the display surface rather than eyepieces in front of the pilots eyes. This has resulted in a family of visor projected displays which cater for a range of requirements from simple day helmet mounted sights to wide field of view, 24 h displays. This paper provides an overview of the visor projected HMD design and technology, discusses the building blocks within a typical HMD system and describes practical implementation for several different applications.