Cross-cockpit collimated display

[1] It is called cross-cockpit collimated because the light from a projected distant object is composed of rays that remain parallel or near-parallel across the cockpit (which typically sits two pilots side-by-side).

[2] The technology was developed in the early 1980s by the British electronics company Rediffusion, and has since become the industry standard for FFS visual systems.

[3] In the real world, the rays of light emitted by a distant source are virtually parallel to each other when they reach two observers standing side-by-side (Figure 1).

Early digital visual systems for flight simulators consisted in one or more translucent screens, directly illuminated by one or more projectors from the opposite side to the observer (Figure 2).

[3] After the patent expired, it was adopted by full flight simulator manufacturers worldwide, and remains to this day the standard for FFS visual systems.