Multi-depth augmented reality display

An imaging system for generating multi-depth virtual images on a screen of a head-up display comprises an image realisation device (300, figure 1) for realising a plurality of first images and projection optics (800) for rendering a plurality of second virtual image corresponding to the first images on the screen of the head-up display. The image realisation device comprises an image realisation surface (IRS) 400 having a plurality of regions 401, 402, 403, each at a different distance from the focal point of the projection optics, and a plurality of surfaces 701, 702, 703 which direct light from the IRS towards the projection optics. The surfaces and IRS are arranged such that a first image realised on one region of the IRS will render an image on head-up display at a first apparent depth and a second image realised on a second region will likewise produce an image at a second apparent depth. Two or more of the surfaces are beam splitters with differing reflection/transmission ratios, selected such that the brightness of the images corresponding to the surfaces are equal. A method of using such a system is also claimed.