Compact head-up display and waveguide therefor

Abstract

A pupil expander for a head-up display. The head-up display has an eye-box having a first dimension and second dimension. The pupil expander comprises a pair of first waveguides (700, 700’) each arranged to replicate a pupil in the first dimension of the eyebox. Each waveguide is elongated and tapered in the direction of elongation such that its input end is narrower than its output end. The first waveguides are arranged so that their input ends are substantially proximate each other and their respective output (702, 702) ends are substantially distal from each other.